We all know how it feels to have a cold coming on: a pain in your sinuses, tickle in your throat, and heaviness all over your body. You’re getting sick, and you start cursing yourself for not scrubbing your hands after exchanging a handshake with your coughing coworker or logging enough hours of sleep each night.

Nobody wants this to happen, which is why you need to keep your immune system in infection-fighting shape. And the secret to that isn't that complicated. “If you take care of yourself, the immune system will take care of itself,” says Timothy Mainardi, MD, an allergist and immunologist based in New York City.

Read on for the healthy lifestyle habits you can practice in your day-to-day routine to cut down on sick days, and keep your immune system strong and ready to fight off any virus.