Just watched Running on the sun: The Badwater 135. And such a great documentary it is. I just cannot recommend it enough.
Badwater Ultramarathon is considered one of the toughest races in the world. 135 miles across Death Valley in mid July with temperature as high as 50 degree Celsius. I first read about it in Ultramarathon Man where Dean Karnazes writes about his experience. Then I got to know a few others who finished it including Scott Jurek and Reza Baluchi an Iranian ultra runner.
So if you are in need of inspiration, get the hold of this film.