David is so committed that he even trains in his sleep. In his apartment, he has set up a hypoxic tent, which reduces the oxygen content enough to simulate being at an altitude of 15,000 feet. David sleeps in what is the equivalent of a base camp at Mount Everest. "What that does, in effect, is it builds your red blood cell count. I've been sleeping here for a month," he says.
With his leaner build and increased red blood cells, David is ready to learn his breath-holding technique. He flies to the Cayman Islands to train with free divers. Free diving is diving very deep without oxygen. After training, David is able to take a single breath and dive down to as deep as 200 feet. Will all of this preparation be enough?
In an interview the day before his world record attempt, Oprah asked David where he got the idea to attempt this dangerous record. "I think it dates back to childhood," he says. "I was on the swim team in Brooklyn at the YMCA, and I was competitive even back then. ... I remember trying to beat everybody doing lengths in the pool. The best way to do it was to not breathe. So when I was swimming the length [underwater] ... I was able to actually go faster than every other kid."