Being flexible means not only developing flexibility within your body, but also being able to adapt to changes on the mountain. A good skier must learn the importance of adjustment and develop an awareness of this key component to skiing well.
Stein actively scans the environment to become quick, flexible and effective in every situation. His flexibility won him a Gold Medal. Of course it helped that Stein also developed great flexibility training as a gymnast for 7 years.
His fluid Stein Turns involve letting the body move in a flowing, gracious and very flexible manner. Not everyone will want to or be able to do those kinds of turns, but being flexible will help you in any style of turn you choose.
There are many exercises you can do before the ski season to develop flexibility such as stretching, especially the legs. There is also a mental flexibility that a good skier must have on the mountain. This involves making good choices on the hill. Being willing to choose a different run if one appears too challenging. Postpone skiing when feeling exhausted. End the day when your legs get wobbly and do something else. That mental flexibility will help keep you from an injury.
Being flexible means knowing what is constant and what is not. Techniques are always changing but our bodies and how they move and work remain pretty steady. And gravity never fails to work on a mountain. The best skiers and the safest skiers develop a healthy sense of flexibility.