Lay on your back with the exercise ball between both feet. Squeeze the ball and lift it with your legs to roll back and touch it to the ground behind your head. "Fifteen times will kick your ass," says MacMillan. Alternatively you can roll the ball in a giant circle with your legs, passing it above your head, and then reversing the direction.
Powered By ZergNet
Sign up to receive the Men’s Journal newsletter and special offers from MJ and its marketing partners.
56 Perfect Things
Tech, Tools, Toys, & the Hottest New Gear
Plus: The Deadly Thrill of BASE Jumping
ON NEWSSTANDS NOW