Running 13 miles to the top of a Colorado fourteener, mostly on singletrack, will alter your understanding of runner's high. The key to minimizing the hurt, says six-time winner Matt Carpenter, is to take it easy on the 13 switchbacks in the first three miles—the steepest section of the course—and start picking off runners on the wider, easier section above them. The aid stations are too far apart for mid-pack runners to stay fueled, so bring a few gels to avoid bonking. And no matter what the weather is like down low, bring gloves, a hat, and a jacket for above tree line. "Hypothermia will slow you down," says Carpenter. $95; pikes­peakmarathon.org