The famed trainer of Mike Tyson Cus D'Amato had a spectacular theory on what made fighters tired. Fear: “Fear is the greatest obstacle to learning in any area, but particularly in boxing. For example, boxing is something you learn through repetition. You do it over and over and suddenly you’ve got it. …However, in the course of trying to learn, if you get hit and get hurt, this makes you cautious, and when you’re cautious you can’t repeat it, and when you can’t repeat it, it’s going to dela