This is a harder one. It requires strength in the upper back muscles to extend the spine. It also challenges the shoulders as you pull your arms in toward your chest. You can use a dowel rod or something similar to hold on to.

Remember to engage your abdominals as you lay on your belly. Try to avoid taking that extension all the way down into the low back and compressing the lumbar spine. If you feel that compression, tuck your tail between your legs and that should help you engage your core more and use your low back less.