[Luyt]

Good idea, I will try that. However, I read on WikiPedia: "Some people recommend sitting on an exercise ball instead of a chair (for example, an office chair). This is based on the theory that the abdominal and back muscles are constantly engaged and active in order to maintain proper posture and balance on the ball. There is no scientific evidence of those benefits occurring by just sitting without additional exercises. However, some people warn against using a Swiss ball as a chair due to ergonomic considerations." http://en.wikipedia.org/wiki/Exercise_ball