4 Secrets to Never Getting Sick

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Make friends with fresh air

Common wisdom has it that staying indoors, where it's warm and toasty, is easier on your immune system than being outside in the cold. Problem is, being inside puts you in close constant contact with other people—and their germs.

Not only does escaping into the fresh air give you a break from all those germs circulating inside, but going for a stroll can actually boost your immunity. "Exercise leads to an increase in natural killer cells, neutrophils, and monocytes, which ultimately increases immune function," says Ather Ali, ND, MPH, assistant director of Complementary/Alternative Medicine Research at the Yale-Griffin Prevention Research Center.

Next: Relaxation fights off colds