I hate sitting in a chair all day. I feel all cramped up and stuck in the shape of a chair when I get up. I was reading a fitness magazine while sitting in a chair at a doctor's office, and there was an article about little 'workouts' you can do that take no extra time out of your day. One of those was to swap out your desk chair for an exercise ball! It makes you use your abs and back to keep you balanced rather than relying on a chair to do it- a little more effort than just sitting on a stool. Sounded good to me, and since I'm already the office weirdo I thought I'd try it! So here I am, sitting on a giant ball! I've already gotten the parade of people with questions and silly comments, and it wasn't as bad as I expected! I find it pretty comfortable, really, since the thing conforms to me rather than the other way around in a chair. So anyhoo...if anyone tries it, lemme know! I got mine at Target. I think it was somewhere around $30 (came with a video tape). The brand I got comes in small, medium, large. I got the large, but I think I should have gotten the medium (I'm about 5'3").