As the ski season gets under way, the last thing skiers and snowboarders want is their first day to be their last. According to physiology Professor Robert Mazzeo of the University of Colorado at Boulder, your best chance at staying injury free is to stay in shape. "Fatigue is one of the primary causes of falls, which are the major cause of injuries," said Mazzeo. "The best way to battle fatigue is to get into shape." Mazzeo suggests the following activities for getting into shape: