Mountain climbers boost cardio endurance while strengthening the core, shoulders, and legs. How to Perform: Start in a plank position with hands under shoulders. Drive one knee toward your chest, then switch legs quickly. Maintain a fast pace while keeping your core engaged. Variations: đ Slow Mountain Climbers â Focus on controlled movements. đ Cross-Body Mountain Climbers â Drive knees toward the opposite elbow. đ Elevated Mountain Climbers â Place hands on an elevated surface.