1. Lie on one side with your knees straight. Prop your upper body up on your elbow and forearm. Brace your core by contracting your abs. Raise your hips until your body forms a straight line from your ankles to your shoulders.
2. From the side plank position, raise your top leg as high as you can. Lower your leg to return to the side plank position. Continue raising and lowering the top leg for the allotted time. A good goal is 30 seconds.
3. Repeat the movement on the other side of your body for the same allotted time. Modification: If you are unable to do the leg lift from a full side plank position, bend your bottom knee 90 degrees and perform the leg lifts.