Feminine and sweet, Stacy Keibler is also a tenacious fighter when it comes to her workouts. A fan of Barry's Bootcamp in Los Angeles, the dancer and girlfriend of George Clooney enjoys the class, which is split between high-intensity cardio and weight lifting. The key to the workout is not knowing what to expect. Recently she was spotted leaving the class after 60 minutes of running treadmill intervals before completing sets of crunches, lifting weights and holding minute-long plank positions. If you want to shock your body this season, sign up for Barry's Bootcamp or a bootcamp-style workout for a great energy burst, no matter the weather outside.