If you asked me a few years ago I would have said football. I played football in high school and college and I loved it.
Nowadays, as I'm older and wiser, I think I'd say baseball. I'd still make a ton of coin, plus retain that ability to walk I've become so fond of.
Better yet, maybe golf. Golfers never get hurt, and they get to wander around in the sunshine all day.
Now I feel like a wimp. I'm changing my answer back to football, and I'll play hockey and maybe compete in mixed martial arts in the off-season.