This exercise is designed to teach you how to use your core muscles correctly. Lying on your back with your legs bent and feet flat, place your hands over your bellybutton. Breathe normally, and as you exhale, bring your bellybutton towards your spine and hold it. Don’t allow any other part of your body to move. Release, inhale, then repeat on the exhale. Do 12 repetitions. Once you learn how to engage your core like this, you should be able to do so during every exercise that you perform. This will protect you from injury and give you better results. If I was standing with you while you were exercising, I would be reminding you to “pull your bellybutton in” during each exercise.