The Pilates 100 or 'Hundred' is one of the best exercises anywhere for keeping your belly firm and flat. If you know anyone who does Pilates, you know what we mean. In this how-to video clip filmed especially for Gaiam Life, Pilates expert Mari Winsor walks you through the correct way to do the 100. She shares tips and common mistakes, plus the benefits you'll get from doing this classic Pilates exercise. Beyond tightening the abs, it also tones the core and arms and boosts energy and circulation…Try it when you need a late-afternoon pick-me-up!