One field that was always fascinating
Motivation and Determination
Here's the list of successful people: Arnold Schwarzeneggar, Elon Musk, Steve Jobs, Owen Cook, Dan Pena, Jack Ma, Larry Ellison, John Carmack, Alex Becker, Michael Jordan, Stephen Curry, Michael Phelps, Nate Diaz, Connor McGregor.
Specifically in numbers what does that work ethic look like?
120 hour work weeks if they were an entrepreneur. 3 hour plus physical training every day if they were an athlete.
So it goes without saying that if you want to maximize your chance of success, you should expect to put in just as many hours as they did.
But what about Burnout?
I say it's how you (your mind and body) physiologically reacts to stress. If everyone is working 120 hour work weeks, the people who have developed the best anti-stress regimes are the ones poised to take the title for #1 (or industry leader, World Champion, etc) in their field.