Still laying on your back — knees bent and feet flat on the floor — place the ball between the inner thighs.
Squeeze the ball between the inner thighs and try to focus on your pelvic floor muscles lifting (think Kegel) and your belly button then pulling deep toward the spine.
Exhale as you squeeze the ball through the inner thighs, lift through the pelvic floor muscles, and pull the belly button toward the spine.