1. Go outdoors, even when it's cold. Even on cloudy or overcast days, your skin can still synthesize some vitamin D from the sun's ultraviolet (UV) rays. Aim for at least 15 minutes of unprotected skin exposure each day, preferably between 10 a.m. and 4 p.m.

1. Include vitamin D-rich foods in your diet. Some good sources of vitamin D include fatty fish (salmon, tuna, mackerel), egg yolks, fortified milk, and mushrooms that have been exposed to UV light.

Take a vitamin D supplement. If you're not getting enough vitamin D from sunlight or food, you may want to consider taking a supplement. The recommended daily intake (RDI) of vitamin D for adults is 600 IU, but some people may need more.

Pay attention to calcium, too. Vitamin D and calcium work together to keep your bones strong. If you're not getting enough vitamin D, you may also need to increase your calcium intake.

1. Talk to your doctor about your medications. Some medications can interfere with the absorption of vitamin D. If you're taking any medications, talk to your doctor to make sure they're not affecting your vitamin D levels.