Do you avoid running hills as much as running in cotton socks? Don't fear the hills! Incorporating inclines into your runs is the best way to increase your speed, build your endurance, and tone your lower body — something running on the flats just won't do. In order to power up those steep rises, you'll need strong quads, calves, hamstrings, and glutes. Here are five exercises all runners should include in their strength-training routines in order to tackle those challenging hills.