Enforcing breaks away from the screen

There's a need to interrupt oneself, to avoid spending too much time constantly staring at the screen/sitting down, etc. to prevent RSI, eye strain, back injury, etc.

• RSIBreak - Looks promising, but falls prey to multi-monitor taskbar bug and is hidden behind taskbar, also greying out of screen doesn't work. And doesn't seem to always alert me. And "lock screen" button doesn't work. Nor does "run on startup". (Ubuntu 12.04).
• Workrave - In some ways looks better than RSIBreak. Easier to configure/understand notification times, has numbers countdown instead of a clock, and suggests exercises to do in the breaks. But it doesn't match up small breaks with long breaks like RSIBreak does, so it often pops up an alert soon after I've just taken a break.