The recipe for keeping colds and flu at bay is pretty straightforward: Wash your hands, don't touch your face, get a flu shot, eat your fruits and veggies, and rack up plenty of shut-eye. But when it comes to exercise, the guidelines may seem a little fuzzy. Exercise can either help or hurt you in the battle against bugs. Dodging these 4 common blunders, however, can help you stay sniffle-free this season. And for goodness sake, always remember to wipe down the gym equipment before and after you use it! (Want to pick up some healthier habits? Sign up to get daily healthy living tips delivered straight to your inbox!)

Mistake #1: Skipping yoga class

Unrolling your sticky mat at a yoga class or practicing with a video at home is so worth it if you want to fend off illness this season. In a study, people who practiced yoga for about 40 minutes daily experienced a significant increase in immune-boosting compounds and a decrease in stress hormone levels over 12 weeks compared with those who didn't Down Dog, reports The Journal of Alternative and Complementary Medicine. "Yoga activates the relaxation response, which lowers levels of adrenaline and cortisol and brings down pro-inflammatory cytokines that can compromise your immune system," says Eva Selhub, MD, author of “Your Health Destiny: How to Unlock Your Natural Ability to Overcome Illness, Feel Better, and Live Longer.”

Mistake #2: Not exercising regularly

If the winter weather has derailed your walking workout, it's time to invest in some layers or a gym membership. Thirty minutes of moderate-intensity physical activity, such as brisk walking (or swimming, jogging, dancing, or cycling), increase levels of ick-fighting immune cells such as immunoglobulins, neutrophils, and natural killer cells, according to a study in the Journal of Sport and Health Science. People who exercise most days of the week decrease their risk of the common cold by up to 50% compared with their couch-potato counterparts, the study found. Plus, levels of those cells remain elevated for up to 3 hours afterward. "Every time you exercise, your body recruits important immune cells from your peripheral tissues into your bloodstream where they recirculate through your body at a higher rate and increase your body's ability to combat viruses and bacteria," says study author David Nieman, DrPH, director of the Human Performance Lab at Appalachia State University. (Having trouble finding time to work out? Try the Fit in 10 DVD for amazingly effective 10-minute workouts.)

Mistake #3: Overdoing it

"By 75 to 90 minutes, unrelenting activity, such as marathon-paced running, turns a good thing for the immune system into a bad thing," Nieman says. Basically, your brain perceives a long period of hardcore endurance exercise as a stressor and pulls the brakes on your immune system. That's because your brain picks up physiological cues that happen when you're in danger: Your carbohydrate stores are depleted, your body temperature is elevated, and your muscle cells breakdown. The good news if you plan to push yourself this winter? Activities with built-in breaks, such as downhill skiing, rowing, and lifting weights won't tax your body in the same way (and can even burn more calories than running). Even if it's intense, your immune system handles intermittent activity much better, Nieman adds.    

Mistake #4: "Sweating out" a fever 
 "The idea that you can sweat out a fever is a serious myth," Nieman says. "When you feel a cold or flu coming on, ease way back." If you have the flu—and it's usually difficult to know early on which is the cough-causing culprit—you can increase your risk of serious complications when adding exercise to the mix. "During exercise, blood flows through your heart at a rate that's about five times higher than normal," Nieman says. The flu virus can become concentrated within your heart and lead to inflammation of the lining of your heart, a condition called endocarditis that can damage your ticker. "While moderate activity neither helps nor hurts when you have a cold, exercising when you have the flu may not only cause a worse and more prolonged illness, it can be deadly," Nieman adds.

This article originally appeared on Prevention.com.