One of the most common pieces of advice for new writers is “Keep your seat in the chair.” The downside is that it becomes all too easy to sit at the desk for hours without moving. This can lead to stiffness and circulation issues even with an ergonomically correct desk and chair.
Ergocise.com is a program which pops up a reminder to stretch at pre-set intervals. The reminder shows a very simple animated gif with an ergonomically correct stretch designed for someone at a desk. Most of the stretches take thirty seconds and none take more than a minute.
So if you find yourself getting stiff after a day in the chair, check out ergocise.com