Ditch the "must-run" mentality when it comes to the treadmill without missing a challenging workout. You can increase walking's calorie burn 50 percent by simply upping the incline or speed. During the first half of this routine, you'll climb a steep hill, forcing your butt and legs to work hard to propel you. The more those muscles fire, die faster your heart beats-and the more calories you torch. Just when your glutes and quads are thinking about begging for mercy, you'll lower the incline and pick up die pace to keep die calories ticking away. So go ahead and "cheat" on your run today-with diis walking routine, you'll never feel like you're slacking off.