Make your own basic Workrave

Make your own basic notification that you should take a pause.
If you find workrave too much. http://www.workrave.org/download/
Go to System tools Scheduled task. or gnome-schedule in teh terminal
and give it a name Pause Reminder.
Choose a moment (I do it hourly on the whole hour).
And give this command:
zenity --display :0 --warning --text="Ten minutes break. Getup and move a little to the groove."

Or another message that may inspire you.
If you don't have zenity:
sudo apt-get install zenity