Brittle bones aren't just a problem for grandma. Women's skeletal systems start to get thinner around the time they hit 3-0, but don’t worry how many candles are on your next birthday cake. Research shows that regular, high-impact exercise increases bone density, and a stronger spine equals a longer life. Do 10 bone-boosting box jumps daily: Stand with feet hip-width apart and arms at sides about a foot away from a sturdy foot-tall box or bench. Bend knees, swing arms back, and jump up on top of the box with both feet at once. Land with bent knees to absorb any impact. At the top, stand up straight, then step off the box or jump down with bent knees. Source: Austin Malleolo, CrossFit head coach at Reebok CrossFit One in Canton, MA
