Bag a 14er (July–October 2014)
Credit: Robert Bossi / Getty Images

Then another. Hiking 14,000-foot peaks, or even ones above 10,000 feet, is essential for developing leg strength, increasing lung capacity, learning to breathe calmly and slowly while moving sluggishly at elevation, and withstanding high winds and cold temperatures above the treeline. Start with day hikes, then work up to overnights, bagging two or more high peaks in a trip – and getting used to carrying a heavy pack. If you live far from the high country, fly to Denver and try Quandary Peak (14,265) in the Mosquito Range and Mount Bierstadt (14,060) in the Front Range, or head for Durango and the San Juans, which have 13 peaks over 14,000 feet. (New Hampshire's famously nasty Mount Washington is also a good practice ground.)