Lately, making little changes has produced major results for us. I’m halfway considering adding an exercise ball in place of my desk chair for all or part of the day. The main setback is that I think it looks so ridiculous! I think this ergonomically designed stool called the Ergo Ergo would be a very happy medium. It costs about the same as an exercise ball + chair kit, but it looks interesting and not necessarily out of place in an office if you decided to roll your regular desk chair back in for part of the afternoon. They seem to be mostly for sale at quirky modern art museum stores, which probably bodes well for them!