Lie on your left side and prop yourself up on left elbow, keeping it directly beneath shoulder. Place right hand behind head and bend knees slightly, bringing feet off floor and rolling back onto left butt cheek (where your pocket would be). Contract right obliques (side of torso) and pull knees and right elbow toward each other, bending at waist as you do. Hold for a second, then release and repeat. 15-20x each side. To make this exercise easier, you can just hold your raised legs in the air while on your butt cheek. Or you can just work the lower half (bringing knees in and out) or just the upper half (crunching downward toward the knees). To make it harder, dont support yourself on your elbow. Once you have rolled onto your butt cheek and lifted your feet off the floor, place the support arm across your belly or fold it across your chest. When you crunch, draw lower elbow to upper knee. This is the version I prefer.