Workrave

Workrave is a free software application intended to prevent computer users from developing or aggravating occupational diseases such as carpal tunnel syndrome and repetitive strain injuries. The software periodically locks the screen while an anime character walks the user through various stretching exercises and urges them to take a coffee break. The program depends on the GTK+ libraries, and will function on Microsoft Windows or any operating system running X11.

Similar RSI-prevention utilities include RSIBreak, xwrits and the "Typing Break" feature in the GNOME keyboard preferences tool.