rachelmanija has a review of an article and the documentary about the Barkley Marathons ("the race that eats its young") which segues into a fascinating discussion of why extreme physical challenges can appeal, and what you might want (or not want) to do if you could wave a magic wand and make it possible for you: if you could, would you want to try the Barkley?
rachelmanija:
The Barkley Marathons and pushing your limitsI think this might be relevant to many people's interests, and there's already some very interesting discussion happening in the comments.