Photo: Mike Baird, Flickr

About a month ago, while running from one end of the supermarket to the other in a mad rush, I tripped over my flip flop and went flying across three check-out aisles, hitting the concrete-hard floor. But because I do push-ups regularly, all I suffered was severe humiliation and a bruised knee.

When we fall forward, we typically reach out and our hands hit the ground first. If we're strong enough, our wrists and arms absorb much of the impact. Researchers who study the biomechanics of aging say push-ups are an effective way to strengthen your upper body so you can break a fall safely. If that's not enough incentive to get you into them, how's this: You'll also sculpt enviously sexy cocktail dress arms and shoulders. Ah, now I have your attention.

"The exercise is regarded as the ultimate measure of physical fitness for a reason: In order to lift your entire body weight, you need to engage almost every major muscle group - the arms, chest, abs, hips and legs," says Adam Feldman, a personal trainer in Nanuet, NY. So it's damn hard. But when you can drop and do 10 without a sweat, you'll feel a sense of pride you just don't get from doing a bicep curl. "We included a push-up in the Challenge this year and women felt strong and empowered when they were able to master it!" espouses Self's Fitness Director, Meaghan B. Murphy.

Start with 10 reps, three times a week. Do as many classic push-ups as you can, then if necessary, switch to your knees. Try to add a classic each time. Work your way up to three sets, three times per week. Once you've gotten that down, try these after-40 variations to specifically target sag spots.

• Triceps. Touch thumbs and forefingers so hands form a diamond shape.
• Butt. Lift right leg off floor six inches; keep it straight. Do your 10 reps, switch legs.
• Abs. Do one push-up. Then lift right knee to right elbow and return to start. Lift left knee to left elbow. Return to start to complete one rep.

If you have weak wrists like me, check out these push-up handles.

For more sexy arm moves try this workout.