Pass The Ball

Lying down face up with your arms above your head, grab a Swiss ball with your ankles, lift your legs and reach up with your hands to grab the ball. Bring the ball behind your head and lower your legs back down to the floor, without touching. Bring your legs back up towards the ceiling, simultaneously bringing the ball up towards your approaching feet. Take the ball with your ankles from your hands and lower them down to the floor. Repeat.

If it's too difficult to lower your "empty" legs all the way down or it strains your back, lower your legs only slightly when your hands have the ball