Julia Hu met her co-founder when she was 14 years old.

He was her teammate for National Science Bowl, a jeopardy-like competition. They went to school together, practiced together, and found out pretty quickly how well they worked together. They ended up winning nationals that year.

Hu is now the CEO and co-founder of Lark, a personal weight loss and health coach — basically, it’s an app that’s a personal nutritionist in your pocket. She and Jeff Zira, that guy from the science bowl team, moved to the Bay Area and started the company in 2010. Now in its fifth year, Lark is one of the top Apple HealthKit apps and is pre-installed in all Samsung S5 phones.

Originally from Los Angeles, Hu was interested in science, but also had a passion for art, and specifically, painting. She attended Stanford for undergrad, where she studied business and design. While she was in school, she interned for seven startups. She was a designer, but she realized she didn’t want to pursue it as a career.

“I really love being the glue, being the person that jumps around and looks at what needs to be done and doing that or filling the gap,” she said. “I really enjoyed a cross disciplinary role, [it was] almost schizophrenic at the time.”

After college, Hu was part of the founding team of three cleantech startups. She had also studied environmental engineering, and wanted to merge that with entrepreneurship and design. The second one she launched is now the world’s largest cleantech incubator, called Cleantech Open.

“I’m kind of an idealist, so I wanted to help save the world and make it a better place somehow… I thought that climate change was one of the big issues — that and healthcare [were] the two big things I was interested in,” she said.

After about four years in the startup world, Hu went to MIT’s Sloan School of Management for her MBA. She was excited about starting a company, but she wasn’t sure what yet. While there, she met a Stanford researcher who coached sports stars and Olympic athletes to break world records by using data to get them to sleep better.

“It was such an amazing story of how to use personal health data to improve your life, and so I was really interested…what if everyone could have a personal health coach based on their own data?” she said.

A personal health coach could allow people to have an incredibly different experience than what Hu had growing up — visiting the doctor or specialist every few months. When she was a child, Hu suffered from chronic stomach issues, which stemmed from an illness that affected her gallbladder. Throughout her life, she wasn’t very active because she had to manage what she ate, and make sure she ate healthfully always. She couldn’t overstress or overexert herself, or she’d experience immense pain.

At MIT, she started planning out Lark. She priced it, researched the market, and started developing the app. She and Zira raised some money through MIT, but weren’t flush with cash. Hu was confident she had something big, so she quit her MBA program, and moved to the Bay Area.

“I felt like I really have found what I love to do and it felt like if I didn’t give it my all it would become another class project,” she said. “My first companies, I was always [regretted that] I didn’t gamble enough, didn’t push it as far as I could because I was scared of failing. So [I thought] I’m just going to try.”

Lark started out as a hardware and software company, making devices and the software to help people sleep better. But over the last five years, it has dropped the hardware and expanded to a better software company that uses sensors from smart phones, with the goal of helping people live healthier lives, lose weight, sleep better, and stress less in a simpler way.

It’s a “Siri for health,” Hu said, and the team has developed advanced AI to make sure Lark is half-friend, half-coach, and an empathetic personal nutritionist that’s in your pocket 24/7.

“I’ve really tried to stay resilient and be open to what our customers are telling us and what the market is telling us,” Hu said, “and continually push the boundaries instead of being stuck to one milestone or one way.”

It’s been a long journey for Hu and Zira, but it isn’t even close to being over. Not only is Lark growing, but there’s also some other news for the long-time couple. They’re engaged to be married.

In her own words…

How do you unplug?

“Funny, Lark has kind of helped me live a more balanced life. In the very beginning, I was sleeping like four hours a night and eating unhealthy, and I kind of got some of my chronic disease problems back, and so now besides having a much more balanced life and exercising, I dance. I love hip hop and dance hip hop. I still love design and art so I paint on the weekends sometimes.”

How did you get into hip hop dancing?

“I realized that I will exercise more if I like what I’m doing. I was in Crossfit for a while but I was like I like dancing a lot more, I’m just going to go dance.”

Looking back, what advice would you give yourself?

“I think that when I was younger I was more scared of failure and I love the idea of failing forward, tell my younger self to fail forward. To me, that means you’re not doing your best if you’re not failing all the time and learning from your failures. If you don’t learn, you’re just failing. If you can pick something up and apply that to your next big gamble, then things work out. We had to walk away from our device and hardware — millions of dollars of revenue because we believed we needed complete focus on building a health AI software that was so good it felt like a buddy in your pocket. That was a really big gamble for us, and in many cases, we basically gave us our successful parts of company. We had to scale down and become an unsuccessful startup again in order to pursue this direction more true to what we could help the world with.”

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