I need help on the stability ball abs section. When you get to the planks off the ball, I can't do any of that part. What am I doing wrong? I feel like I'm gonna hurt myself! Any tips on doing this would be helpful. I LOVE the workout otherwise. Some of the combinations I'm gonna have to learn and become more familiar with, but it was a lot of fun. The best 68 minutes I spent all day! Thanks for any help.