Vitamin D, that is. You'll need it to aid in the absorption of all that calcium you'll be ingesting. Fortunately, your own skin produces vitamin D in response to sunlight. Getting just 10 to 15 minutes of sunlight exposure two to three times week should enable you to meet the vitamin D requirements for most people. Drinking vitamin-D-fortified milk can also boost your intake, but consider with caution a dietary supplement, since too much vitamin D can be toxic.

Exercise has been proven to help prevent osteoporosis, as the pull of the muscles against the bones spurs the building of more bone cells. In particular, weight-bearing activities such as jogging, walking or stair climbing can help build bone strength, as can resistance exercise using free weights, fitness bands or weight machines.