Although you can’t make your breasts bigger, you can give them a lift (and create sexy cleavage for that low-cut dress) with exercises that firm the pectoral muscles beneath your breasts.   These chest fly and push-up exercises are two moves that do just that. I’ve made them more challenging by showing you how to do them on an exercise ball (available at sporting goods stores). Other muscles, including your abs, also get a miniworkout as they stabilize you.   A beautiful bust improves your figure and boosts your confidence. And having strong chest muscles makes it easier to push a cart loaded with groceries.   Your Toning Program Do two sets of 10 repetitions of each exercise, allowing 30 to 60 seconds of rest between sets. Move slowly: 3 seconds to lower, 1-second pause, 3 seconds to lift. Do two or three sessions a week, with at least 1 day of rest between workouts.     Chest Fly on an Exercise Ball     Sitting on a large exercise ball, inch your feet forward, and roll your body down until your head and upper back are supported. Your feet should be hip-width apart, knees over your ankles. Contract your buttocks, and raise your hips until your body, from the knees up, is parallel to the floor. Hold a pair of dumbbells with your arms extended over your chest, elbows bent, and palms facing each other. For a printer-friendly version of all steps click below.   Note: Skip this exercise if you have orthopedic problems such as painful knees, hips, ankles, or back.     Keeping your abs contracted and your wrists straight, slowly lower your arms out to the sides in a smooth arc. Pause when your hands are chest level, then sweep both arms back up, squeezing your chest muscles. Stop before the dumbbells touch over your chest, then repeat. (You can also do this move on an aerobic step or with pillows stacked underneath your back to allow elbowroom.)     Push-Up on an Exercise Ball     Kneeling in front of a large exercise ball, rest your torso on top, and extend your arms so they reach over the other side. Slowly roll your body over the ball, and inch your hands forward on the floor until just your thighs are resting on the ball. Your hands should be in line with your shoulders but slightly more than shoulder-width apart. For a printer-friendly version of all steps click below.     Keeping your abs contracted and your back straight, bend your elbows, and slowly lower your torso toward the floor. Stop 4 to 5 inches shy of the floor. Hold, then push back up. (For an advanced version, rest just your shins on the ball. If you don’t have an exercise ball or are a beginning exerciser, start with a push-up on the floor with your knees bent.)