Winter exercise can be downright frustrating. You've worked hard to improve or maintain your fitness level, but the wind chill makes you want to stay inside. Fortunately, cold weather is no reason to stress about getting sick—the National Institute of Allergy and Infectious Diseases has found that cold viruses actually grow best at about 91 degrees. Freezing temperatures won't make you sick directly, but they can cause quite the shiver.

When I moved to Maryland from North Carolina for college, I had a hard time adjusting to the colder climate (Bostonians—I know, I’m weak). However, running on the cross-country and track teams forced me to adapt. We ran in anything and everything. Torrential rainfall, near-blizzards, over roads covered with snow, sidewalks slicked with ice—you name it. I had my share of frostbite-inducing moments, like the time I forgot mittens on a seven-mile run in 20-degree weather. Or the time I ran a cross-country race during the middle of December in Iowa wearing shorts, a tank top, and only gloves (see the photo below—I'm the one grimacing on the right).

Eventually, I learned how to dress for warmth during my workouts. Some might say I’m crazy, but I love exercising outdoors in the winter. The air is crisp, humidity is low, and best of all—no sweat-soaked clothes. Plus, a steamy cup of coffee is the perfect incentive to finish a tough run.

Is there a rule of thumb when it comes to what to wear? Everyone is different, but here's a good place to start: Layer up and aim to dress for 15 to 20 degrees above the actual temperature. Cover your core area first, as losing heat here leads to hypothermia. Next, focus on your hands. In the coldest temperatures, wear mittens over gloves. Address your head, legs, and arms after your core and hands. Based on my experience, here are the guidelines I follow:

50°F and above: No need to layer. Shorts, short-sleeves, or a sleeveless shirt should do the trick.

35°F to 50°F: Try shorts or cropped running tights. Start with a long-sleeved running top over a short-sleeved shirt and a pair of lightweight gloves for temperatures in the 30s.

20°F to 35°F: For temperatures in the 20s, opt for long thermal running tights and a long-sleeved base layer top. A thicker half-zip running top with long-sleeved or short-sleeved shirt underneath will also work. Fleece or wind-resistant mittens and a headband or beanie hat are musts.

10°F to 20°F: Dress the same as you would in 20- to 30-degree weather, but consider wearing thicker socks and a neck gaiter. Try to limit the amount of exposed skin,especially in windy weather.

Below 10°F: Frostbite is a serious risk in temperatures below 0°F. Be smart and workout indoors.

Want to show your friends how hardcore you are for beating the freeze? Take the #100HealthyDays challenge and share the badge, "I braved the cold for my workout."