Bad news: according to Ferraro, your lower abs are the trickiest place to get definition. The solution: "Getting a good dose of classic left lifts in will help you whip them into shape," he said. "Lay at the base of your bed, and grab the post. Slowly lower your legs to the floor, keep them locked out straight, and do not let your heels touch the floor. These burn baby!" He recommended doing three sets of 10 to 15 reps.