There are a few keys to getting your body ready for skiing, the first being endurance, and not the kind that you build running on a treadmill. The reason that your legs are so sore the day after skiing isn’t because your legs are weak, but rather because they’re not adapted to spending the amount of time under tension that they do on the ski slopes, so this needs to be the focus of our training. The other areas that need to be addressed in order to help prevent you from getting injured are balance and core strength/stability.