in all variations the core and arms should be engaged, shoulders stabilised and the pelvis tucked in. Try holding the pose on your knees, then take the pose further by lifting the knees off the floor, lifting one leg or lifting the opposite arm and the leg as well. Once strength is built, try Side Plank (Vasisthasana), either one knee on the floor, both feet on the floor or one leg extended to the ceiling. Finally Reverse Side Plank (Viparita Vasisthasana). Tip: arms are not designed to carry our whole body weight so engage your core and legs to make the pose easier.