Marathons are just a warmup.
Taking on a marathon isn't that unusual these days, as you know from the guy in your office who keeps asking for a donation to the charity he’s running to support. You may even know an ultrarunner, which refers to anybody tackling more than 26.2 miles at a crack—but generally 100 miles. Then there’s Dean Karnazes, who dropped off his kids at school on a Wednesday morning and went out for a run. When he stopped, he’d covered 350 miles and it was Saturday. While he was upright the whole time, he claims that at some points he was "sleep running."
Image © Halfdark/fstop/Corbis