I love this exercise! It’s a plank, on a ball, with moving parts. It doesn’t get much better than that for me. And Kelly does an amazing job demonstrating and showing how you can make the exercise a bit easier, if it’s too much. But, my favorite part is when she shows you how to make the exercise even more challenging by adding movement in a different plane. It’s a concept called perturbation and it’s so cool and so challenging – so make sure to watch the short video clip to the end. Enjoy!