When I'm coding or writing reports, I often find myself going into a trance-like state where I can't keep myself from looking away from the monitor. That is majorly bad, and I know it, but sometimes I just don't care because things have to be done. I figured I needed something external to enforce a little discipline in me, so I'd got Break Reminder. I used it for some time. Unfortunately, I'd turned it off when I found it unbelievably annoying. Before you start rolling your eyes, let me say that I find my "unrepentant" behavior very disappointing as well.
So now having been alerted to WorkRave by Simon Willison, I've decided to install it and enforce breaks no matter what. It isn't a good sign when your wrists, fingers, neck and back start to ache. I needed RSI prevention, fast.
WorkRave is an Open Source application that sets reminders to tell you when it is time to take a break from your work. Oh, and it's free software. I've it set to micropause for 20 seconds every 8 mins, and enforce a rest break of 5 mins every 45 mins. The FAQ has some guidelines for good timer values. If you've ever felt any aches in your wrists or fingers, or find yourself unable to take a break from your computer even though you know you needed it, get it and try it out. There're Windows and Linux versions - having a Linux version is great, because now I can enforce breaks when working in Linux too.
Source: Simon Willison: Avoiding RSI