Does working out in the cold actually do something weird to your lungs—or does it just feel like it?

It’s a sad day when the temps drop, turning your breezy fall runs into 10-layer, freezing-cold sprints straight back to your warm, cuddly blanket. Even though winter can’t stop you from hitting the pavement, there’s one thing that might be bothering you during your outdoor workouts: the weird—and sometimes painful!—sensation you get in your lungs from breathing in the icy air. But is something bad actually happening to your lungs, or does it just feel like it?

When you’re simply walking around outside in cold weather, you’re probably breathing through your nose, giving that ice-cold air time to warm up before it hits your lungs. When you’re exercising, on the other hand, you’re taking deep, quick breaths through your mouth, so the cold, dry air hits your lungs as-is, creating a sensation that despite feeling weird isn’t anything to worry about. “Cold weather can cause your airways to spasm, leading to symptoms such as shortness of breath and chest tightness. But unless you have asthma and other lung diseases, exercising in cold weather isn’t harmful to the lungs,” says John Prucha, MD, a doctor at UCHealth.

Even though working out in the cold doesn’t harm your lungs, that feeling still isn’t at all enjoyable. Luckily, there are some simple ways you can exercise outdoors a little more comfortably. “To reduce these symptoms, you can cover both your nose and mouth with a scarf or thin face mask while exercising. This warms and moistens the air prior to inhalation, decreasing the likelihood of having these symptoms,” Dr. Prucha explains. And that’s a good idea anyway: Those low temps can seriously mess with your complexion. “At -18 degrees Fahrenheit, exposed skin can be frostbitten in less than 30 minutes. If the temperature is below 0 degrees Fahrenheit, consider exercising indoors instead.”

Yeah, yeah—running outside is way better than jogging in place on a treadmill like a hamster. But on those ultra-chilly days, it might just be your best bet to keep you and your lungs happy.

These are the eight biggest activewear trends for fall/winter 2018. Or, find out how “daylighting” can help you beat the winter blues before they really get you down.