Alicia Keys (after) MAKEOVER MOVES: Cardio! says DiMuzio. Most cardio activities - running, biking, cross-country skiing, etc. - primarily work the legs. So breaking a sweat a minimum of four times a week for at least 30 minutes is crucial. Add to that this spot-training move from DiMuzio: Stand with your feet together, arms hanging by your sides. Now step with your right leg into a side lunge (right leg is bent, left leg is straight, torso is facing forward). Hold briefly, then push back to up. Do two to three sets of 20 reps on each side.