Lie on your (R) side and pull your (R) knee in toward your chest. This is to protect your lower back. Then pull your (L) heel towards your bum using your (L) hand (or a belt/rope/towel if you cannot reach without straining). Make sure that you keep your lower back rounded (do not arch your back). Stretch smart not forcefully. No knee pain and no back pain. If you are in doubt please contact an exercise professional to assist.