No matter what your workout style, you're bound to come across a plank in your life, and for good reason. The move works the entire body and also creates an awareness that can help in everyday life and activities. Once you've mastered the traditional plank, step it up a notch with a knee driver. If you can believe it, a knee driver forces your abs and shoulders to work even harder. It's also a favorite of trainer Adam Rosante, who is known for killer total-body workout. Add it to your next strength-training routine or challenge yourself during commercial breaks the next time you have a marathon TV session planned.