Windmill on Chair Exercise: A Simple Way to Improve Flexibility and Balance. The Windmill on Chair Exercise is a great way to improve flexibility and balance in your hips, spine, and shoulders. It's also a great way to strengthen your core muscles. This exercise is easy to do and can be modified for people of all fitness levels. In this video, we will show you how to do the Windmill on Chair Exercise safely and effectively. We will also discuss the benefits of this exercise and provide tips for