Well, kinda differs, from person to person. For instance, I have friends who do love cross-fit, sprinting or football. Ofcourse, football is the most popular of them, because it is not something really exhausting like cross-fit. But, there are many others, atletics (from light to heavy-weight), boxing, or MMA. MMA is my favorite one, because during the fight I can appease my feral instincts, and its bloody fun, ofcourse. Not everyone can participate in the MMA matches, because you are required to have good fighting skills, to be fearless, and to be ready to take injuries or even open fractures. Yes, sometimes it happens, but, no pain - no game.