After finishing the New York City Marathon in 2010, former "Survivor" winner Ethan Zohn signed up for a second stint in 2011. But less than a week before the marathon, he announced that his cancer had returned and he was on a chemotherapy regimen. Even so, he finished the race in four hours, 20 minutes and 46 seconds. "My quads were burning, my hamstrings felt like they were about to rip off," he told People. "But I knew with every step I was crushing little cancer cells on the road. I even wrote 'f--k canzer' on the bottom of my shoes. That's what kept me going."