There's something both thrilling and terrifying about joining a company in its early stages — you're never quite sure of what the future may hold. In The First 100 we're highlighting hires #1 through 100 at startups like Vimeo, Thrillist and BuzzFeed that are in a state of constant growth.

This week, we hear from hires #51 through 60: Ten brave employees who decided to take the risk, follow their gut and embark on — what turned out to be — a successful career journey at companies like Eventbrite, Shutterstock and Meetup. If you'd like to hear from more members of the First 100, make sure to check out the series to read up on employees #1-50 and follow the hashtag #First100 on Twitter..

51. Chris Usiak, Equinox

Image: Chris Usiak

Long term commitment... This was never intended to be a full-time, long-term career. I subbed for my brother in maintenance while he went on spring break when I was 13-years-old and never looked back. Twenty-to years later, I am the senior director of sales in New York, overseeing 32 clubs and more than $95 million in revenue. The role came about because of my commitment to the brand and the results that I achieved.

Maximizing members' lives... The company has grown tremendously since 1992. We went through two acquisitions, grew to more than 64 clubs (including locations in London and Toronto), acquired Soul Cycle and Pure Yoga, and introduced Blink Fitness, as well as Creative Juice. We continue to be the leading operator of upscale fitness, and offer high-performance programming to maximize our members' lives. I envision the company expanding into Europe, as well as to new U.S.-based locations, with a continued laser-eye focus on an unparalleled fitness experience.

To another twenty years... I truly believe that fitness is the platform for living an overall better life, and I cannot live without it. Equinox has been a home for me and helped me through some difficult times. The members' results and the membership advisors motivate me to keep going every day. I met my best friends at Equinox and am very grateful. I look forward to another 20+ years.

Today, Equinox has 9,000 employees.

52. Scott Lee, NatureBox

Image: Scott Lee

Embracing the chaos... I joined NatureBox because I wanted to work for a startup focused on smarter living. NatureBox helps people discover a better way to snack, which is very appealing to me, and the vision and passion of Ken Chen and Gautam Gupta, who founded the company, is amazing. I did have some reservations at first: My marketing decisions are driven by data — and that requires a robust infrastructure, which would be a challenge for any small company. But the upside is that I can put my own stamp on that structure as grows, rather than adopting an existing template. I found that the more I embrace the chaos, the more productive and engaged I become. The co-founders have given me the framework — and the freedom — I need to help them scale the business aggressively. It’s a really exciting challenge.

When the stakes are high, embrace the ride... What excited me about NatureBox was that I was heading into something less stable and more scary — but scary like a rollercoaster ride, not like a 'run-for-your-life' scenario. I have broader responsibilities and more provocative challenges. But most of all, the stakes are much higher, and we have much less room for error. I learned quickly that I needed to figure out how to manage and motivate a team of hungry, smart and ambitious individuals. That has been one of the most rewarding experiences since I moved here.

Still in the first inning... All of us are growing into our roles together, which makes it an exciting environment to walk into every day. And when things get crazy, I've learned that I need to consciously remind myself — and my team — of the big picture. Startups can fall into a trap of paying too much attention to the day-to-day and not spending enough time on long-term strategic planning. I've figured out we can work more efficiently if we just spend a little more time mapping out goals and objectives, and understanding how the latest idea will affect each level of the business before we implement it. Even though we've grown so quickly, we still have a huge, untapped audience to reach. That's what keeps me going: We are still in the first inning.

Happy snacking... We are scrappy and hungry, even though we snack all day long. We put our customers first, so all new team members spend time on the phone with actual subscribers and in the warehouse packing orders. We all buy in to the mission of happy snacking. Because we're such a small company, everybody needs to be open-minded and work hard — and that means we challenge one another to do things better than we did the day before.

Today, NatureBox has more than 50 employees.

53. Teresa Hammond, 4moms

Image: Teresa Hammond

An appetite for change... I love working in a company where agile thinking and rapid prototyping rule. We are incredibly nimble and can test new ideas very quickly; there is bias toward action and an appetite to try new things. The organizational resistance to change and risk that I experienced in bigger companies doesn’t exist at 4moms. When I joined 4moms, the marketing team was small, and we all jumped in and contributed to whatever needed to get done. In order to support the company’s aggressive growth goals, we've added some team structure as well as specialists who bring new expertise to the table. With the right people on board (and some clear priorities!) we can focus on the best opportunities to grow the business. Every day I’m doing things I’ve never done before. I've learned more in the past year than in the previous five years.

Shaking things up... The company has more than doubled –- in revenue and headcount –- since I joined. I feel like we are lightyears ahead of where were just 15 months ago. We have incredible momentum and I'm excited to think about where we'll be in another 15 months. We have amazing new products in the works. I know we will continue to shake things up in the juvenile products industry by bringing our “outsider” perspective to solve unmet consumer needs with robotics, technology and design.

Work hard, respect others... The entire 4moms team is passionate about creating dramatically better baby gear and building a successful company that cares about more than financial success. We also have a lot of fun along the way. Our culture the heart of the company, and maintaining our unique culture as we grow is a top priority. The "Words We Live By" really reflect how we work together. My favorite is #7: "Be Humble. Work Hard. Respect Others.”

Today, 4moms has 113 employees.

54. Wyatt Jenkins, Shutterstock

Image: Wyatt Jenkins

A necessary product in a booming market... I wanted a challenge; something where I could leverage my previous experience (with a company called Beatport) of building a two-sided marketplace. Shutterstock was profitable and growing, even through the recession of 2008, (the same recession that slowed growth at my previous company), so I remember thinking that Shutterstock was a product that customers really needed in a market that had potential. One of the things I loved about Shutterstock was how it supported artists; this is a business that helps people be creative, and that keeps me excited every day.

Structure for growth... It is common practice for our people to work on things besides what is outlined explicitly in their job titles — this is the best way to work at a high-growth organization. When I joined, the CTO, chief architect and I worked together to structure the technology group for growth. Within six months, we were dividing up the company into dedicated, cross-functional teams that were capable of iterating on complex problems at high speeds. We hired talent for product, UX and research to help scale. Today, we have 15 product teams supporting everything from search to video, mobile to localization, as well as new businesses such as Offset and Skillfeed. While I am now VP of Product, each team is designed to act like a startup, building and deploying independently and quickly.

Builders and tinkerers among us... Early on, startups are like a kids soccer team — you kick the ball and the whole team goes chasing after it. Now, we've got lots of different teams operating independently. At our scale, that independence can come at a cost — chaos. But we would rather cultivate an entrepreneurial culture: A place people love working, with continuous integration, ownership and all the other great aspects of autonomy over bureaucracy. There are builders and tinkerers among us, many of whom are naturally creative as artists, photographers, videographers, musicians and more. There are marketers who can code and engineers who can effectively articulate the levers of our conversion rates in different international markets.

Breeding startup structure... We have a bunch of really smart, driven people who love solving problems. In 2013, we launched two startups internally — Skillfeed and Offset. We host quarterly hackathons, including one annual, company-wide hackathon where people celebrate building something useful in a 24-hour period. We have a mantra of 'doing,' and one of our developers put it best in a poster that’s now on my wall: "We only hire smart people, therefore you are smart; figure it out."

Today, Shutterstock has 326 employees.

55. Ian Greenleigh, Olapic

Image: Ian Greenleigh

Making sure it's the right fit... Everything lined up in the right way. I had just come from Bazaarvoice, where I was part of several years of truly epic growth, and I think Olapic is poised to follow a similar trajectory. I led the effort at Bazaarvoice to extract insights from our data and share them with the world, and I wanted to do it again at Olapic. Sure, I had reservations. I was moving from Austin to New York, so I needed to make sure we were really a good fit, and that I believed in Olapic’s potential. But the prospect of essentially starting from scratch — building an entire marketing team from the ground up — that’s what really clinched it. Oh, and I liked the founders’ accents.

Feeling a sense of purpose... At first, I had to focus pretty intensely on getting a handle on things that were already in progress — like a new website and conferences we had already signed up for. Concurrently, I went on a hiring spree and brought on three employees and an intern. We’ve grown our staff, expanded internationally and landed some exceptional new clients. There’s also a feeling of purpose, of knowing what we're here to do, that’s stronger than when I started. Now I have some space to think about how to bring the brand to life. I want our insights to be indispensable; I want our marketing to be substantive, not fluffy. I want everyone to know who we are, because we've earned it.

A small, scrappy and social family... What do I love most about Olapic? How cliché is it if I say the people? But, yeah, it’s really the people that surround you that can make or break your day, and we’re like that weird family down the street that you secretly want to join, even if it's hard to believe that they're really that happy. Believe it! We're scrappy, social and eclectic. We have big personalities, and we'll sleep when we're dead.

Today, Olapic has 100 employees.

56. Jennifer Van Hook, GumGum

Image: Jennifer Van Hook

The true test for a salesperson... Before I took the job, I asked clients for their opinion of the product and the response was overwhelmingly positive. That's the true test for a salesperson — do you represent something people want to buy? In this case, the answer is definitively "yes." What excited me most about GumGum was the company's commitment to making advertising work better for brands. GumGum's technology and advertising solution is truly differentiated in an incredibly crowded marketplace. There is a lot of experience steering the company's direction, which gave me confidence about joining a small company.

Success built upon relationships and solutions... I was hired to build the west coast sales team and drive revenue throughout the western region. In my first week at GumGum, I set up more meetings with interested, top-tier clients than I had seen before in such a short period of time. Sales success is based on relationships; but it's relationships plus a valuable solution that leads to booked business. GumGum has very smart leaders with a clear vision about the direction the company is headed. GumGum's investors and advisors are impressive, experienced and involved. From top to bottom, the company is comprised of accomplished professionals who are empowered to manage and run the departments. I see our ad revenue soaring in the next 12 to 18 months. From a sales perspective, I see only growth.

A great team and environment... I learn something new every day. And every day I collaborate with my colleagues to find solutions for our clients. I have a talented team and get to work with smart, wonderful people. It's a positive, inclusive corporate environment and I am excited about the future. That's what keeps me going.

Today, GumGum has 56 employees.

57. Cory Wheeler, FindTheBest

Image: Cory Wheeler

Seizing opportunities... I joined FindTheBest as an intern during my senior year of college at UC Santa Barbara, so it's my first "real job" and where I've chosen to really launch my career. I liked that the company was small enough to know everyone’s name and have everyone’s work truly matter. I was the first intern in our accounting department, and when I began working full-time, I took on the entire accounts receivable side of our accounting operation. After about eight months on accounting, an opportunity arose to join our revenue operations team, where I'm now primarily responsible for advertising operations and revenue tracking. I love that FindTheBest is extremely flexible in allowing employees to move around within the company. If I have a big idea, I'm encouraged to pursue it.

Growing new departments... We've doubled in size since I joined, which is really exciting to watch. We've launched new teams, added new roles and adjusted some of our high-level strategy to address upcoming opportunities. Many of the earlier roles have expanded into departments of three or four people, and I'm sure that’s going to become more and more common as we continue to grow. I'd love to be able to build an entire department out of my current role, and I'm confident that with enough time and growth, we’ll get there. At a startup or growth company, there's minimal bureaucracy, so we can act on new ideas quickly and see how our performance directly affects the company’s success. My role never feels stagnant, which certainly keeps my job interesting.

The team as MVP... The culture at FindTheBest is truly unlike anything I've ever seen. We understand that everyone’s individual success comes together to push the company forward. I really appreciate being surrounded by others who are passionate about the product and their careers, and who are willing to work hard. We all know that it's important to find a balance between team and individual victory. Players on losing teams are rarely the game's MVP, so we work hard to develop each other and grow as a whole.

Today, FindtheBest has 120 employees.

58. Erin Dertouzos, Meetup

Image: Erin Dertouzos

Accepting on the spot... Two things really struck me about Meetup: Hustle and passion. I applied on my lunch break and had my first interview at 5:30 p.m. on the same day. When I interviewed with our CEO, Scott Heiferman, we got into a mild debate about the merits of unions, and I remember walking out thinking "I just disagreed with the CEO of a company I really want to join. I'm either definitely getting the job or never hearing back." I was thrilled when it turned out to be the former, and accepted on the spot. While there was a millisecond where I considered the risks of joining a small company, excitement about building something big quickly took over, and I've never looked back.

Moving mountains... My role has changed tremendously. I was initially hired into a junior HR generalist/recruiter role. After a while, I took on technical recruitment, then oversaw all recruitment. About a year-and-a-half ago, I took on leading the HR function: We now have a team of four that handles everything from building out our team to maintaining our culture. My career goal when I graduated college was to be the head of an HR department; I just figured it would take me a little longer than it did. That's what so special about smaller, leaner companies: If you're smart, ambitious and open to it, you can move mountains.

Face-to-face value... I remember a couple years back when my grandmother came to me and said "I saw a Meetup." She'd been wary of the fact that her only granddaughter worked at a tech startup (and I'm sure imagined the worst). Then she stumbled across a divorce-support Meetup while visiting my uncle, and that's when she "got" it. She saw the people meeting face-to-face and saw that Meetup added tangible value. More and more frequently when people ask me where I work, they know the company and respond in a positive way; I can't wait for the day when people stop hiding behind their screens, and I no longer have to explain what we're all about.

Having fun at work... On even my toughest, most frustrating days, I'm incredibly aware of how lucky I am to be at a place like Meetup. I came back from vacation last year to a desk covered in glittered confetti and streamers. Our general counsel gifted our operations manager a case of wine with his face printed on each label as a 'thank you' (an idea that essentially came from a dare on my part). I've been known to spill a beverage or two (I've gone through at least two dozen keyboards over the years), and rather than a bunch of eye rolls when it happened on Monday (per usual), someone grabbed paper towels and laughed with me — not at me. I'm a firm believer in laughter being an important part of any marriage. And devoting seven years (so far) of my life to Meetup, well, I definitely consider that a marriage of sorts.

Today, Meetup has 106 employees.

59. Nate Jaffee, Mass Relevance

Image: Nate Jaffee

Great product, brilliant philosophy... I was the director of strategy at PUMA before Mass Relevance, and that's actually where I learned about the company. I knew firsthand that the product was great, and I philosophically shared MR's belief that brands need to empower their audience to express themselves. When I learned more about the culture at MR, I was sold. Mass Relevance was one of a very few startups that had both a great product and a proven business model. After spending the last seven years at large companies, I was looking for a small, innovative, growing company. The culture made it feel like the right fit.

Refocus and pioneer... When I started, the priority was educating agencies and brands on why they should integrate social content into their marketing programs. Today, the industry has a stronger understanding of the value of social -– it's now table-stakes for brand marketing, not just an experiment. Now I'm focused less on education and more on building partnerships with an ecosystem of agencies that are using our platform in new, creative ways. Moving forward, we're continuing to pioneer new ways for brands and media to leverage social to market to consumers in real-time. We're also putting a lot of effort into our recent global expansion: We opened an office in London and have strong partnerships with some of the best sports and media companies in EMEA. We're continuing to invest in that area of the business, and look forward to partnering with more international clients.

Freedom is the best policy... The culture is as close to Burning Man as a company can get. Creative expression, community-orientation and self-reliance are part of the company's DNA. Our founders' principles resonate in everything we do — the team is given the freedom to find innovative solutions, be entrepreneurs within the company and create their own career paths. There aren't many rules. We have unlimited vacation and no set office hours. But people are still challenged to do their best work. We love what we do and, in turn, we want to come to work. We've created a culture of people that are self-policing and hard-working. Somehow it all fits together, and the trains always run on time.

Today, Mass Relevance has 131 employees.

60. Paul Pieralde, Eventbrite

Image: Paul Pieralde

A risk worth taking... My reservations on joining Eventbrite were mostly related to job stability. Whenever you are changing jobs, there is a fear of the unknown. I have three small children, and all the financial responsibilities everyone else has, so leaving a really big Internet company (with the security and benefits) to join a small startup (with all the risks) was a big leap of faith. The team at Eventbrite was really helpful and encouraging. Eventually, I decided that the risk was worth it and would be a tremendous opportunity to advance my career. Also, the business model of Eventbrite was attractive: The product is fee-based, and if you build a great product that people love, they will come back and use it again. The alignment with the best interests of our customers was quite appealing.

A demanding role... I was hired as a senior product security engineer, which would lead you to believe that my responsibilities ended with the web apps, mobile apps and production infrastructure. But in reality, if it needed securing, I was responsible. From creating badges for guests, to installation of video cameras to watch the front doors, to IT security and vendors — I am basically on the hook for all that. It is a super demanding position and can be "interrupt driven" too. I did this role solo for three years, and am super thrilled to have hired on our second security engineer to help offload a lot of that work.

Doing things right... The company's evolution has been one of controlled growth. We have not gone into areas that are outside the "sweet spot" for the company. Many times companies will pivot or morph to please a big customer or do something that is not in the long-term interests of the company. We have a clear vision of where we want to be and we iterate and iterate to get things just right. We have expanded globally since I started: We opened offices in London and are in the process of opening other offices around the country and the world. Eventbrite acquired two companies in 2013. These expansions lead to new opportunities for me to evolve my role, and give me new and exciting challenges.

Welcome to Briteland... The company culture is "brite," fun and open. We love orange. We clap when something is awesome. We love dogs. We are transparent, so there aren't too many secrets. We expect great things from each other. There is a high degree of trust and respect in the Briteland. We are global and must think big. The best things about working at Eventbrite are the people, the problem-space, and getting to come to work every day and learn from some of the most brilliant and talented folks — and getting an opportunity to secure the assets of a billion dollars. Lots of challenges!

Today, Eventbrite has 327 employees.