As someone who's really into sports science and biomechanics, Federer is literally the new textbook for more than just tennis. He perfectly illustrates a lot of 'new school' principles in sport, the whip-like smoothness of the Tim Lincecums or Steph Currys or Bruce Lees instead of the more obviously visible muscular power of guys like John Elway or Brock Lesnar or Nolan Ryan.

You know why Federer makes it look easy? Because he's not trying that hard- at least not in the way that many people traditionally think of it. Dude is basically the embodiment of the fact that speed is power, and tension kills speed, and that you generate power from the ground up.

On the mental side, Federer is a basically a case study in channeling competitive aggression- young Roger was more like Boogie than Kawhi. Today he's pretty much Tennis Buddha and I've learned a lot studying both sides of his career.

Compared to guys like MJ or Tiger, I think he's a much better role model. I always thought he had found a great balance of work and life with proper focus on mental health. Clearly he's about as competitive as a human can be, but he also seems like a normal human instead of a killing machine.