Start lying on your side with your bottom elbow under your shoulder, hips and knees stacked, and body in a straight line. Push through your knees to lift your hip off the floor. Keep your hips pushed forward and your glutes squeezed. To progress, once you are lifted, you can continue to lift your top leg into a one-legged side plank. Lower and return to start. To progress more, extend the knees to straighten the legs and stack your hips, knees, and feet. Push up to lift your hip off the floor, keep your hips forwards and glutes squeezed. Again, you can lift your top leg off the bottom to come into a one-legged full side plank.