Here is your exercise that all my participants in the Saturday Intermediate Class had difficulty with. Don’t feel you need to watch the whole set (snoring), just watch to be sure of technique before practicing on your own.
Remember-the further out you roll (i.e. the closer to your feet the ball is positioned), the less stable you are and the more difficult the exercise. Start with the ball more under your thighs and progress to having the ball placed beneath lower shins and ankles.
Work those obliques Baby!