Muscle is harder to build and maintain as we age. In fact, most of us start losing muscle around age 30, with a 3- to 8-percent reduction in lean muscle mass every decade thereafter. This is due to lower testosterone levels in men and lower estrogen levels in women — both hormones that help build muscle — as well as changes in nerve and blood cells and the body not converting amino acids to muscle tissue as efficiently, among other factors.

Strength training is an important piece of the fitness equation. Men and women should participate in muscle strengthening activities that work the major muscle groups (legs, hips, back, chest, abdomen, shoulders and arms) at least two times each week. Examples of strength training include lifting weights, using resistance bands and doing push-ups, pull-ups and sit-ups. Even everyday activities strengthen muscles.