To reach your fitness goals, you hit the gym regularly, target specific muscles, and push the intensity of your workouts. But you might as well throw in the towel if you're not treating your body to proper post-exercise rest and recovery. Muscle fibers broken down during training need time and TLC to heal. Skimp on it, and you're less likely to build strength and endurance. Plus, you could end up with an injury, says Tedd Keating, Ph.D., CSCS, associate professor of kinesiology at Manhattan College in New York City. Below are the nine recovery rules you need to follow to get the most from your hard work.