Join the Five-Mile-High Club (October 2016)
Credit: Chris Noble / Getty Images

"Statistics show that climbers who have topped out on an 8,000-meter (26,000-foot) peak before trying Everest have a much better chance of being successful than those who have not," says Whittaker. So if time and money allow, get over to the Himalayas and climb Cho-Oyu, the 26,906-footer that many Everest summiters have cut their teeth on. Climbing Cho, you'll learn what it's like to share a base camp with wily climbers from multiple countries and to climb with a supplemental oxygen device clinging to your face. You'll taste the homesickness, depression, and physical ailments that plague mountaineers who venture to the higher reaches of the planet. And most important, you'll experience the death zone, which begins at 26,000 feet. "It's not some sexy term," says Freer. "In the death zone you are literally dying. There's not enough oxygen in the brain, so everything goes slower. Sometimes you can barely put a sentence together."