The Bricks: Physical ExerciseThe "why" part of exercise is easy: Physical activity keeps you young by improving balance, mobility, strength, and stamina and reducing your stress level as well as your risk of diabetes, heart disease, and stroke. It’s the "how" part that can get you stuck: how much, how often, how hard, how long? There’s no one place to go for answers, so we did the legwork and put together this exercise pyramid, highlighting the building blocks of a workout for an over-40 woman. The bricks are the physical components of your activity plan — the must-do items to tap the longevity benefits of exercise. The mortar is the mental component that holds your fitness plan together (and helps you stick to it). Use this template to build your own routine, one that you can live with and, most important, enjoy.Everyday moves: 200 calories a day Try to torch a couple of hundred calories each day by ratcheting up your regular activities: Take the stairs, walk to get your errands done, do some of your own housework, and try to beat your time to the mailbox. "These activities alone are not enough to get you in shape, but you will burn those extra calories responsible for fat rolls and weight creep as you get older," says Barbara A. Brehm, PhD, chair of exercise and sports studies at Smith College. Look for any exercise opportunity: If you work in a high-rise building, try to climb 10 flights of stairs a day. You’ll burn 85 calories in just 10 minutes. Carrying groceries for five minutes gets rid of 13 calories. Every little bit gets you closer to your daily goal. For more about how many calories you burn just living your life, go to caloriesperhour.com.Cardio: 30 to 60 minutes, four to five times a week "Cardio really is your key to keeping disease at bay after 40. As you age, your circulation decreases, putting you at greater risk for blood clots and heart disease," says Leslie Sansone, creator of the Five-Mile Advanced Walking DVD (walkerswarehouse.com). With cardio, you’re not only building more blood vessels, you’re making all your vessels and capillaries more efficient, thus increasing your heart and lung strength. "In your 40s, the payoff for working out to stave off disease is actually greater than it was in your 30s," Brehm says. "Cardio keeps your weight stable, which reduces your risk for hypertension and type 2 diabetes." Whatever you’re doing, do it with gusto. "If you are walking, head to a hill or go faster; if you’re on the treadmill, crank up the incline — you can’t get away with cutting corners, the way you could in your 30s," says Pamela Peeke, MD, author of Fit to Live. "You lose muscle faster after 40 — mostly from disuse — so ramping it up helps counteract that." For each session, aim to burn at least 300 calories.Strength training: 20 to 30 minutes, two to three times a week "After 40, the key is lifting weights heavy enough to make a difference in fighting bone and muscle loss," Brehm says. "If you can easily do eight to 12 reps, it’s time to increase the weight to something that feels tough after six to eight reps." Peeke’s favorite strength-boosting trick is to hold the movement. "You don’t have to increase weights to get results," she says. "When you think you’re at the top of a biceps curl or the bottom of a squat, hold and squeeze just a little more out of that muscle." To get the most weight-loss bang for your exercise minutes, do compound exercises — moves that hit multiple muscle groups simultaneously — recommends Robert Ferguson, creator of the weight loss program Diet Free for Life (dietfreelife.com). "Exercises such as squats, lunges, and lateral pull-downs have a greater metabolism-boosting effect because you’re activating more muscles."Specialty work (yoga, Pilates, core): 10 minutes daily "Women think they have to make a huge commitment to yoga or Pilates," Brehm says. "Just a few exercises give you benefits." Cherrypick the best moves, and tack them onto the end of your cardio and strength workouts. Get more ideas from The Pilates Body by Brooke Siler, or the Power Pilates Beginner Workout DVD (powerpilates.com). Strong core muscles will help prevent injury and protect your posture.