For years ive watched it advertised late night on TV. My bf bought me the set a while back, and I thought I was going to die doing them. Im sure they work, however, I couldnt do one darn thing that they were doing, except breathing. Im totally out of shape, and my friend told me it took a while for her to get used to it. However, the only thing I did was the breathing, and when I layed down on the mat, I never got back up.

lol