Pack your gym bag in a way that will keep you warm, healthy, and glowing all Winter long. Since your gym bag is almost of equal importance as your workout and goes everywhere with you, make the most of it this holiday season. Simple swaps like an extra pair of running tights and a Winter-worthy snack will keep you out of a cold-weather rut and going strong no matter what temperatures the weatherman predicts. Here are seven essentials we can't live without!