How I built a $10 billion wearable fitness company

For Will Ahmed, the road to building a $10.1 billion fitness startup began with what he calls “the ultimate betrayal.” The perpetrator? His own body.

Launched in 2012, the Boston-based wearables company now has over 2.7 million users worldwide. Those customers use screenless Whoop wristbands to track a wide variety of biometric data around the clock, from sleep quality to how their bodies perform during exercise and recovery. The company achieved its 11-figure valuation in March, with a $575 million fundraising round from a group of investors including athletes such as LeBron James, Cristiano Ronaldo and Rory McIlroy.

“All my life, I loved sports and exercise,” said Ahmed, 36, founder and CEO of Whoop. He played many sports growing up and eventually became the captain of the Harvard University squash team. He also focused on training to the point of chronic fatigue from “overtraining,” he says: “I would go through periods of getting stronger and stronger, and then all of a sudden I would feel like I was losing energy … and I didn’t know why.

While studying government and economics at Harvard, Ahmed used hundreds of medical research papers to gain insight, he says. He found that fatigue from overtraining can affect anyone who exercises regularly, not just elite athletes. And he became convinced of an underserved market of active, health-conscious consumers who want to better understand “what’s going on, physically, inside this person’s body,” he says.

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Before graduating in 2012, he published his own research paper titled, “The Feedback Tool: Measuring Energy, Recovery, and Sleep,” and began working on Whoop. Working at Harvard Innovation Labs with co-founders and fellow students John Capodilupo and Aurelian Nicolae, Ahmed wrote his first business plan and made the first prototypes with body sensors.

The following years did not go well. Investors repeatedly expressed skepticism about the business, and Whoop nearly went out of business in about six years, Ahmed said.

“I had never started a company. I never had a full-time job,” Ahmed said. “I was doing business at the intersection of hardware and software and data science and medicine, [but] I wasn’t a hardware engineer or a computer scientist, or a data scientist or a doctor. So, I think there was a lot of doubt.”

Ahmed funded Whoop’s early days with an undisclosed amount of money from friends and family, he says. He spent much of 2012 trying — unsuccessfully — to woo big investors, receiving a total of 143 rejections during the company’s early years, he estimates.

Nike had just launched its FuelBand activity and wearable calorie tracking device in January 2012. The long-rumored Apple Watch followed two years later. “[Having] two of the best and biggest companies in the world, with Nike and Apple, as your competitors are not very good,” said Ahmed.

Investors suggested replacing the software that other companies build for wearables, but Ahmed was convinced that the surest path to long-term success was to build “the entire system end-to-end,” including both the hardware and the software that powered it, he says.

“It was a very difficult time … every day I just tried to pick myself up and put one foot in front of the other and keep building,” Ahmed said.

For him, the distinguishing feature of Whoop would be the extensive biometric data – including, eventually, blood pressure and ECG monitoring of the electrical activity of your heart – which at the time, was mostly available with large, invasive devices in medical centers. To collect that data, he needed to build wearables that could collect it effectively. Ultimately, that challenge helped Ahmed secure $3 million in seed funding in July 2013 from a group of venture investors led by the Collaborative Fund.

With funding in hand, Whoop can finally turn Ahmed’s ambition into a tangible product. Whoop’s founders led the way in computer science and mechanical engineering, with Nicolae becoming a senior hardware engineer.

The company started by developing individual pieces of technology — such as LED sensors that use light to measure heart activity and blood flow passively, for example — and then worked to integrate them into a wristband. Its first product entered the market in September 2015.

Whoop first revealed a number of top athletes, hoping that high-profile endorsements would provide instant cachet for the brand. Ahmed came to them through their trainers and performance coaches, he told the “How I Built This” podcast in the July 2025 episode. In September 2015, Whoop users included NBA star LeBron James and swimming legend Michael Phelps.

But popular customers haven’t translated into loyal sales, Ahmed said. In 2017, Whoop was still unprofitable, and sometime that year, the company was “one week away from declaring bankruptcy,” he said, adding: “The technology was very powerful, but we hadn’t figured out how to make a real business out of it.”

Professional athletes might pay $500 for a fitness band, but the general population could not, and Whoop needs a large volume of sales revenue to cover its research and development costs, Ahmed said. In 2018, Whoop changed its business model to an annual membership package starting at $199 per year. Members get their fitness band and access to the Whoop app, which includes a raft of health and fitness tracking tools, as well as free software and hardware updates when they’re released.

Whoop’s subscriber base grew, starting slowly and growing exponentially during the Covid-19 crisis when consumer interest in tracking their health grew, the company told CNBC in October 2020. The company ended its 2025 cash flow after new memberships doubled annually, Whoop announced on March 31.

But the market for wearables is not as competitive now as it was in 2012, and is still dominated by products like the Apple Watch – which sold an estimated 281 million devices during the first decade, reported Wired in April 2025. There is also Fitbit, which Google acquired for $2.1 billion in 2019, and a rival that recently competed was like one billion to track our health. October.

Ahmed plans to further grow Whoop’s subscribers by adding more customers overseas – its members currently live in 200 countries – and invest more in technological development, including artificial intelligence, he says. Launching Whoop out of college was “one of the scariest decisions I made in my life, because I didn’t know what I was signing up for,” he says.

Some entrepreneurs should follow their instincts and trust their gut, he adds. “It was a big leap of faith,” Ahmed said. “The lesson I took [is] sometimes you have to jump big… if that’s what your inner voice tells you is right for you. For me, that inner voice I had at the age of 22 was screaming: ‘You have to build this company.’

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