In April 2003, Aron Ralston went solo into Utah’s Bluejohn Canyon, dislodged an 800-pound boulder, and spent five days with his right arm crushed against sandstone a hundred feet below the rim and twenty miles from help. He rationed two burritos and a few sips of water, then drank his own urine. On day five he snapped both bones in his forearm and spent an hour sawing through skin, muscle, and tendon with a dull two-inch multi-tool blade. Then he rappelled, hiked, and lived. The arm stayed with the rock.