3 Ways Your Body Is Wearing Out (and How to Stop Them)
"The cartilage in the kneecap wears down naturally, but you can strengthen the knee if you work on your quadriceps and hamstrings."
Get Stronger: Squats and lunges (3 sets of 10, three times a week)
2. Achilles Tendons
"Over time, tendon cells lose their elasticity. In your Achilles tendon, which connects your calf muscle to the heel bone, that can mean less flexibility and more aches and pains—but building up your calf muscles lessens the force on the tendon."
Get Stronger: Calf raises (3 sets of 15 daily)
"Aging tendons can also cause shoulder problems, especially when you lack upper body strength. Concentrate on the muscles in the front and back of the shoulder."
Get Stronger: Modified push-ups (from knees) and seated rows using 5-pound dumbbells (3 sets of 10 each, three times a week)