Sitting still is particularly unhealthy and very uncomfortable. The knobs and levers on traditional task chairs have kept people sitting still for decades.
Freedom changed that.

Niels Diffrient replaced the locks, knobs and springs that are under older generation chairs with your body weight and the laws of physics so you can move effortlessly from one position to another, making it feel as if the chair were custom-made for you or whoever happens to be sitting in it at any given moment