think about it, on sportscenter when an athlete from another sport gets hurt, and then returns into the game after the injury, the announcer always jokes "he's tough, he's a hockey player" showing that its a well accepted fact that of the 'traditional' team sports, hockey players are amongst the most mentally and phyically tough. to me that mental toughness one gets from playing years of ice hockey, translates perfect to the mental toughness and patience one needs for jiu jitsu.