Can someone provide a website that shows proper form so I can make sure I'm doing it right? I don't want to hurt my back. How many should I do to get a firm tushy... and how often? I don't have far to go because I don't need to lose weight, and my legs are pretty strong from walking, swimming, Pilates, and weight-lifting. I would just like to have a rounder, firmer butt and thighs by Halloween, LOL. Thanks in advance for any input.