He’s a model for success.

On Tuesday, at Tesla’s annual shareholder meeting, Musk answered a fan question about what he does in his spare time. “I listen to music in the car,” Musk said, and then struggled to think of other things, Quartz reported. “I do watch movies, although less these days … Hang out with kids, see friends, normal stuff. Sometimes go crazy on Twitter,” he said. “But usually it’s work more.”

Indeed, Musk works up to 100 hours a week, and has said that “creating a company is almost like having a child … It’s almost like, how do you say your child should not have food?”.

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He’s not alone in following a punishing work ethic. Marissa Mayer has described how she made a 130-hour-work at Google possible by being “strategic about when you sleep, when you shower, and how often you go to the bathroom.” Other execs that burn the midnight oil — and then some — include Mark Cuban, who says that he once “had so many jobs my parents wondered if I would be stable,” and Tim Cook, who starts sending work emails at 4:30 am.

Of course, all of these people likely had an innate talent, but experts say it’s hard work that has probably made them the successes they are today. “Nobody is great without work,” concluded an analysis of years of data and studies on success by Fortune Magazine. “It’s nice to believe that if you find the field where you’re naturally gifted, you’ll be great from day one, but it doesn’t happen. There’s no evidence of high-level performance without experience or practice.”

There is some evidence that you’ll need to practice roughly 10,000 hours on something to be great at it and to be pretty good roughly 7,500 hours, but this doesn’t entirely explain success. Indeed, one study found that the time you work on something only predicts about ⅓ of the variation in performance. Other factors that are in play may be intelligence, innate ability and personality.

Still, there’s no substitute for hard work. Just ask Elon Musk, who when asked in 2013 what entrepreneurs should do if they want to succeed, answered, “work like hell.”