Harley Pasternak 5-Factor Workout Circuit

Harley Pasternak's Favorite 25-Minute Workout

Harley Pasternak's Favorite 25-Minute Workout

Stars like Katy Perry and Rihanna save time when they work out by using celebrity trainer Harley Pasternak's 5-Factor workout philosophy: 25-minute workouts, five days a week.

Harley's workouts break down to a simple formula: five minutes of cardio, 15 minutes of strength training, and five more minutes of cardio to cool down. This may not sound like much, but trust me: it's effective! After experiencing my own 25-minute Harley workout at a training camp sponsored by Subway, I was thoroughly convinced — and sore. If you want to try it yourself, then do the following workout, which is a favorite of Harley's because you're either lying down or seated for the entire strength-training portion of the workout. "I love that you're focusing on muscle fatigue rather than general fatigue," he says.

To begin, start and end with five minutes of cardio, like jumping jacks or jogging. Then grab a mat, a medicine ball, two dumbbells, and an exercise ball, and repeat the following three-move circuit four times (for a total 15 minutes).