Nothing gets me more out of breath than..well moving in general but working out. My step-sister has an ab ball and I thought I would give it a go and see what I can do. I gotta be honest, the ball was so squashed underneath me that it was burning my legs more than my non existent abs because I had to hold my weight up. I just end up bouncing on it instead and my huge double belly just moves so lovely..quite mesmerizing if you ask me. I'm so glad it didn't pop below me but you can definitely tell how much it gets squished under me. Enjoy!