Say what you want about ultra runners, but I came away with a lot of respect for Rob Krar after watching this. The footage is stunning if you just want to watch on mute.
Have always wondered if there's a link between depression and distance running. I happen to suffer from the occasional bout (nothing as debilitating as Krar mentions, I've never been incapable of leaving my bed, but I have stayed inside for days on end.) A decent chunk of runners I know tend to be on the depressed side as well.
More on Krar:
http://www.runnersworld.com/trail-runner-profiles/the-contradiction-of-rob-krar