Remember that you burn more energy in the cold because your body needs to circulate blood through your extremities as well as warm the cold air that you're breathing in. Peanut butter and honey sandwiches are easy to make and safe to store in a locker along with fresh or dried fruit. Just be sure you don't have a nut allergy. Other easy, yummy and portable choices are fruit and yogurt, or cheese and crackers. Crispy rice squares, puffed wheat squares or other cereal-based snack are good sources of iron and B vitamins.
Cookies are also energy-packed because they are a good source of carbohydrates.
Aim for oatmeal raisin cookies, Daniel bars, or granola cookies or bars for the more nutritious choices. If you're buying food on location, go for sandwiches, soups, muffins and hot chocolate. Try to avoid sodas, pops and other artificially-flavored drinks. Your body has to use more energy to process these carbonated drinks instead of giving it to your muscles. Chocolate bars are high in fat, but choose ones with peanuts in them, for the most concentrated energy.