Cross-country skiing is a highly aerobic activity that can generate a lot of body heat. Your clothing needs to protect you from the elements while allowing sweat to quickly move away from your body so you don’t overheat. If it doesn’t, you risk getting chilled (or even hypothermic) once you stop. When cross-country skiing, wear multiple lightweight layers of clothing for warmth and versatility. This allows you to add or remove layers as needed and it creates the most insulation during your winter activity.