So many of our daily movements go from front-to-back—walking, running, climbing stairs—that we sometimes forget we also need to train our bodies sideways. Working your inner and outer thighs, obliques, and side glutes will round out your strength. Plus, you'll work those crucial muscles for stability on your feet. Translation: You'll improve your balance, be more toned, prevent injury, and even run better. Side step ups get you moving in the right direction, with the added aerobic component for a metabolic boost. When doing this move, keep your shoulders square and your step light, especially on the landing.