Do Gym Ball Exercises Really Work?

Being a certified couch potato, I cannot help but noticed these gym ball exercises being promoted in Home Shopping Netework. The users looked happy and seemed to be having a real good time.I was thinking that they need to project a happy image since they are endorsing something to the public. If they show the truth then people will not buy. They need to look good to successfully entice the viewers. By some strange twist of fate, I received a free trial membership of a local Pilates club. I cannot deny that I am a free loader. I did not waste this golden opportuity and tried it.