3. FLIRT WITH DISASTER
In 1995, Karnazes ran his first Badwater Ultramarathon, a 135-mile trek that starts in Death Valley, California, in the middle of summer and finishes at the Mt. Whitney Portals, 8,360 feet above sea level. After running 72 miles in 120-degree heat, Karnazes collapsed on the side of the road suffering from hallucinations, diarrhea, and nausea. He had pushed himself to the point of death to find out whether he was strong enough to survive. He was. Though he didn't finish the race that year, Karnazes came back the next and placed 10th. He won it on his fifth attempt, in 2004. "Somewhere along the line, we seem to have confused comfort with happiness," he says.
6. SHOW YOUR BODY WHO'S BOSS
"The human body has limitations," Karnazes says. "The human spirit is boundless." Your mind, in other words, is your most important muscle. As a running buddy told him: "Life is not a journey to the grave with the intention to arrive safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming: Wow!! What a ride!"