To some, running is the best form of cardio out there, a full-body exercise that leaves them feeling refreshed and strong -- that "runner's high" is no joke. To others, running is literally the incarnation of everything terrible in the world. (Is that extreme? Maybe, but it's true.) Taking off on a lengthy endurance run or even just a quick set of sprints either brings groups of people together or draws thick lines between them, so which side do you hang out on?