ScreenRest

ScreenRest is a straightforward and easy-to-use application which reminds you to take regular rests from your computer. Using ScreenRest gives you complete control over how often, and how long, you wish to rest. You have the choice of being reminded to take rests at fixed intervals, or having your keyboard and mouse usage monitored to determine when it is best for you to take a rest.
When a rest is due, ScreenRest will pop up a reminder dialog onto your screen. The dialog will inform you what kind of rest you should take (a rest break or a microrest), as well as the duration of your rest. Whether or not you have the option to cancel or delay your rests can be specified by preference settings. Once you have started your rest, ScreenRest will keep the dialog active, counting down the time to make sure you take the full of amount of time for your rest. This helps ensure you get the benefits of taking regular rests from your computer.