As co-founder and CEO of Tough Mudder, he first experienced the frantic early days, trying to keep up with explosive growth as the obstacle race phenomenon took hold at the beginning of this decade.

Now in a more stable era, Dean runs a company exponentially more complicated than it was at launch, as he guides it from being a mere event operator to a worldwide media and marketing brand.

“People say, ‘Will, you’re not getting a bit bored?’” Dean says. “And the genuine answer is, I think I’m in my third career. Not third job, but third career, within Tough Mudder.”

Each of those eras has demanded a different skill set from Dean, who started out as a counterintelligence employee with the British government before attending Harvard Business School. But the original wisdom of Tough Mudder, then way ahead of its time, still holds true: A new generation sees sports as an active, social experience first and a display of elite talent second.

Stadiums replacing lightly used seating with bars and flagging TV ratings for the NFL might be storylines of today, but in 2010 Tough Mudder bet that millennials would pay for the right to complete a grueling obstacle course as a team and not even be timed, much less ranked. Dean says the company “spotted which way the wind was blowing” with young people.

“I think it’s in no small part because people are spending more time on their phones, on Facebook, and less time with their friends,” Dean said. “So when they are together, they don’t just want to be sitting in a stadium watching professional athletes run around and not really interacting with each other.”

The changes and growth of Tough Mudder have challenged his weak spots as a leader, Dean said. But he adapts and tries to make good hires and stay self-aware. “As a young CEO, I think the most important thing is acknowledging what you do and don’t know, and being cool with that.”

— Ben Fischer