Holy Moly, as soon as I stepped on it my back felt a "letting go of tension" is all I can say.  I thought I'd use it for small bursts at my standing desk, but I don't think I ever want to get off of this.  I have an anti-fatigue mat which I've been using and thought was doing its job quite well -- was feeling better standing for 7.5 hours a day than sitting, and I'm 55 years old and had 3 knee surgeries about 24 years ago, so I thought the anti-fatigue mat was just fine --  but I wanted to alternate between that and other mats and/or foot massage balls --  in order to use different muscles so I can feel even better after standing a whole work day.  ThisAirex Balance Pad  is more comfortable than the anti fatigue mat though, don't know if I'll be going back to that :)