Watch Jiri Prochazka swim 30 meters under a frozen lake

Jiri Prochazka | Photo by Harry How/Getty Images Jiri Prochazka continues to test his limits in unconventional ways.
A former UFC light heavyweight champion, Prochazka is known to be one of the more eccentric personalities in MMA. Back when he was champion, Prochazka spent three days without water in a dark room as a form of mental training, saying it allowed him to “work with his demons.” Before that, Prochazka would punch trees up to 500 times a day in preparation for his fights. N