Aron Ralston - after 2 years (from Associated Press)

Malnutrition and dehydration, delirium, searing pain - none of it registered anymore. Held captive by a half-ton boulder at the bottom of a narrow canyon for five days, Ralston freed himself by severing his own arm, gaining an unexpected second chance at life.

Resigned to death the night before, Ralston felt more alive than ever, glowing from what he believed to be the close of one life and birth of another.

And he hasn't stopped living in the two years since.

"At this point, I've got the confidence to know that I'll get through anything in my life given I have the motivation to do it," Ralston said. "If it's an act of survival, we've all got a reason to keep living. It may not be pretty, but surviving is grit and determination in its highest form. I learned that I've got the capacity to do a hell of a lot more than I thought I could if I have the proper motivation."

Heading out on a relatively benign - at least to an experienced mountaineer such as Ralston - hike through a slot canyon in the Utah desert in April 2003, Ralston became trapped when a chockstone dislodged and trapped his right arm. With little food, less water and virtually no chance of being rescued, Ralston used drastic means to extend his life, from drinking his own urine to rigging ropes and webbing to support his weight.

Unable to budge the boulder with a makeshift pulley system or break it with a multi-tool, Ralston escaped by torquing his arm against the rock to break his bones, then ripping through his decaying flesh with a small, dull knife.

His bloody stump wrapped in a makeshift sling, Ralston rappelled down a 60-foot drop, then hiked six miles through the desert before an improbable sequence of events, including stumbling across a family of hikers and getting to a helicopter just in time, helped save his life.

It was a staggering display of human will and survival, and the tale spread inspiration across the world.