You must develop hip flexibility, tone the side and lower abdominals, and strengthen the lower back.Bicycle TestLie on your back, knees over hips, feet dangling in the air. Place your hands behind your head (keep elbows open wide and don’t lace the fingers). Try to touch your right elbow to your left knee as you fully straighten your right leg to hover above the ground. Return to the center position without touching your shoulders to the floor. Switch sides, and repeat. Take at least two seconds to do each side. Each time you touch elbow to knee on both sides, counts as one rep. Keep count until you can’t do another set. If you get to 20, you’re finished. Your Score/Biological Age Reps Body Age 17 to 20 20s 13 to 16 30s 10 to 12 40s 8 to 9 50s 5 to 7 60+ Fitness RxWhat works: The bicycle test, which works all your abdominal, side, and midsection muscles, as well as the hip muscles. Other core-building activities: Pilates, yoga, dance, martial arts, and core-focused classes at the gym. How often: Three 30- to 60-minute sessions a week.Flexibility: Reach TestFlexible muscles and joints help you maneuver better in the world (for example, looking over your shoulder to back the car out of the driveway). What’s more, stiff joints and tight muscles can also set you up for injury: Reach beyond your range and you risk getting a sprain or strain.Reach TestSit on the floor with your right leg straight in front, foot flexed. Place your left foot against your inner right thigh, left knee open to the side. See how far you can reach toward the toes of your right foot. Using a tape measure, quantify your success: If your hand can reach beyond the toes of your flexed foot, measure by how many inches. If your hand doesn’t reach your foot, measure the distance between the fingertips and foot as a negative (for instance, if your fingers are 2 inches short of reaching your toes, count that as -2). If you can reach the toes but no farther, give yourself 0. Repeat on the other side. You’ll end up with two scores, and one side will probably be more flexible than the other. That means you need to work on the tighter side more, with the goal of becoming equally supple on both sides. Reaching even a quarter inch farther is a worthwhile improvement.Your Score/Biological Age Inches Body Age 3 20s 2 30s 1 40s 0 50s 1 or less 60s Fitness RxWhat works: The reach test targets every muscle on the back side of the body, from your foot to your neck. Round out your routine with stretches that work the muscles on your front and sides. Peeke also suggests yoga. How often: Ideally, one 10 to 30-minute session a day.Balance: One-Leg Balance TestYou need it every time you step from one foot to the other, so this is an essential if you want to be able to walk when you’re 80.One-Leg Balance TestStand near a wall or chair so you can get support fast if you wobble. Balancing on your right leg, move your left foot onto your calf. Then start the timer and see how many seconds you can stay in that position with your eyes closed. Repeat on the second side. You’ll end up with two scores, and one side will likely be better than the other. Work harder to improve the weaker side so that you become more stable.Your Score/Biological Age Seconds Body Age 16 to 20 20s 14 to 15 30s 12 to 13 40s 10 to 11 50s 8 to 9 60+ Fitness RxWhat works: Balancing on one foot while brushing your teeth is a good way to improve stability. After you master that move, try standing on a small firm pillow or a wobble board. You’ll also improve if you take up skating, yoga, hiking, or dancing.How often: One 5- to 10-minute session at least twice a week.Cardiovascular Endurance: Step TestWhen your cardiovascular system is fit, blood carries oxygen to your muscles as you need it. That means you can run for a bus without feeling as if you’re going to die. Cardio fitness is associated with maintaining a healthy weight and heart.Step TestUsing a timer, step up and down on a curb or a step for three minutes. Stop, then count your pulse for 15 seconds, placing two fingers (not your thumb) on the inside of your wrist. Multiply by 4 to find your beats per minute.