obviously not in such a technical way as boxing, but its basically how hard a punch you can take or give.

The top ten most difficult sports to play, according to this list, are boxing, ice hockey, football, basketball, wrestling, martial arts, tennis, gymnastics, baseball/softball, and soccer.

Dr Cleere's answers:

1
1 Swimming. Most swimmers fall into what I call the seven-day self-sabotage cycle. ...
2
2 Gymnastics. Gymnasts are very similar to swimmers. ...
3
3 Tennis. Some tennis players struggle with self-sabotage and nerves a week before a tournament. ...
4
4 Golf. ...
5
5 Baseball.