Day 13: Log Off at 9 P.M.
Using your computer close to bedtime upsets your circadian rhythm, making it harder to fall asleep. The monitor's bright display inhibits production of melatonin, the hormone responsible for telling the body it's time for bed.
Day 14: Take a Vitamin D Supplement
Unless you live in Yuma, Arizona—the sunniest city in America—you're probably not getting enough vitamin D (which the body absorbs from ultraviolet rays) during the winter. And it's hard to load up on D through diet alone—a cup of milk only has about 100 IU and most experts now recommend 800 IU. A vitamin D supplement helps defend against Parkinson's and Alzheimer's diseases, keeps bones healthy, and may prevent autoimmune diseases.
Day 15: Floss Twice a Day
Even on mornings when you're rushing to get out of the house—and nights when you're ready to collapse into bed—don't neglect your brush-and-floss routine. (You can now find floss made with super strong GORE-TEX, infused with mouthwash, and more.) "Your mouth harbors 400 to 800 kinds of bacteria, which have harmful effects on overall health because they allow unwanted germs to enter the bloodstream," says Violet I. Haraszthy, Ph.D., an associate professor at the University of Buffalo in New York. "This can predispose people to diabetes, respiratory diseases, rheumatoid arthritis, obesity, osteoporosis, cardiovascular diseases, and cancer."
Day 16: Snack on Some Cherries
Cherries have been found to fight inflammation that may lead to heart disease, arthritis, and cancer.
Day 17: Do a Breast Check
Monthly self-administered breast exams up the odds of detecting a tumor early, when it's more apt to be successfully treated. "Start by raising your arms over your head in front of the mirror before showering so you can spot any discoloration, redness, discharge, dimpling, or unusual markings," says Marisa Weiss, M.D., president and founder of Breastcancer.org. "Then place your hands on your hips, which engages your chest muscles and may reveal any abnormalities." Follow up by palpating your breasts with soapy hands while you're bathing—it's easier to feel subtle changes when your skin is wet and slippery.
Day 18: Call a Pal
Just one day of feeling down can cause an increase in the amount of the stress hormone cortisol circulating in your body, which over time can contribute to a host of diseases, says Louise Hawkley, Ph.D., a senior research scientist at the University of Chicago. So beat the blues by making plans to get together with friends.