Reason #5 to Lift Weights (Adam Campbell)

5. You’ll Build Stronger Bones 
Just like muscle, you lose bone mass as you age, too. This increases the likelihood you’ll one day suffer a debilitating fracture in your hips or vertebrae. That’s even worse than it sounds, since U.K. researchers found that among older women who break a hip during a fall, more than 50 percent will never walk again. In addition, significant bone loss in your spine can result in the dreaded “Dowager’s hump,” a condition that leaves you with a hunchback. The good news: A study in theJournal of Applied Physiology found that 16 weeks of resistance training increased subjects’ hip bone density, and elevated their blood levels of osteocalcin—a marker of bone growth—by 19 percent.

Another bone-related benefit: Researchers in Georgia found that osteoarthritis sufferers who performed leg exercises through a full range of motion three times a week reduced knee pain by up to 58 percent.