Second, pregnancy and menopause also can weaken your midsection. As a baby grows in the womb, the surrounding abdominal muscles stretch outward. If you don’t tighten up those muscles after delivery, your abs will remain loose and weak. Third, and probably least fair of all, some people are just genetically predisposed to store fat in their midsections. To turn things around, however, you only need to spend about 12 minutes, 2 or 3 days a week, to whip your abdomen into shape. Here are some exercises that will help you to target specific core muscles: Your Upper and Lower Rectus Abdominis Fibrous bands of tissue break up this large muscle that runs from your pubic bone to your ribs along the front center of your abdomen, creating the six-pack appearance. Though the rectus abdominis really is one large muscle, I like to think of it as two distinct ones—one below the navel and one above it—since you must perform one type of exercise to tone the upper area and another exercise to tone the lower section. Your Transverse Abdominis The stability ball can really help tone this muscle. This deepest layer of the abdomen lies underneath your rectus abdominis and helps you contract your abdomen and draw your belly inward. Strengthening it creates a natural girdle for the front and sides of your midsection. Your Obliques Internal and external obliques form your sides and waist. Your external obliques sit closest to the surface toward the front of your waist, with the internal obliques sitting deeper and closer to your back. Toning them shrinks your waistline and love handles. [pagebreak] Your Lower Back Your lower back contains numerous muscles. One group, called the erector spinae, attaches to your spinal column at different points along your back, allowing you to bend it forward and backward and from side to side. Toning these muscles helps prevent back pain, and it also tightens and firms your entire lower back. That’s handy for shrinking love handles or any other back flab that may stick out over your bikini, underwear, or low-rider jeans. The following exercises zero in on these core muscles. When doing each exercise, pay careful attention to your body alignment. A few repetitions of an exercise done correctly—to completely work your abdomen—are better than 20 sloppy ones. Remember: quality over quantity. For most exercises, perform up to 12 repetitions. In a few of the movements, you’ll simply hold the posture up to 1 minute.

Pelvic Tilt

Benefits: Firms your lower belly; stretches your lower back This is a great warm-up exercise. I like to do it at the beginning of an abdominal routine to ready my abs for harder movements.  A. Lie on your back with your arms down near your sides, palms facing down. Grasp the ball between your feet with your legs extended at a 90-degree angle to your torso. You’ll really feel it in your inner thighs. B. Exhale as you curl your lower belly toward your upper belly, lifting the ball up and in. Inhale as you lower. Continue to lift and lower the ball up to 12 times. More from Prevention: 25 Best Toning Moves For Your Most Stubborn Trouble Spots