Most experts agree that boxing is the toughest sport, though what people find hardest can change from one person to the next. Getting into boxing means being strong, having endurance, a tough mind and being able to move fast—while taking hits. It takes years of training for athletes to compete at the best level. However, MMA, ice hockey or gymnastics could also be candidates, based on the judgment criteria. What you may find difficult in sports, like speed, strength, skill or strategy, is what will lead you to say that What is the hardest sport is. All sports put different and serious demands on our bodies and minds.