Are you sitting comfortably? Hopefully you haven't been sat looking at your VDU like Bristol computer programmer Chris Simmon who almost died of a deep vein thrombosis due to sitting at his computer for long periods of time without a break.
Apparently, Simmon's condition is believed to one of the first diagnosed cases of what has been dubbed as "e-thrombosis" - similar to the condition increasingly associated with flying for long distances in cramped conditions.
So, if you have been sitting at your desk for more than an hour or so it's time to get up for a stretch and a walk around the office or wherever you are working. When you come back read the following article for more details - Immobile office workers given DVT warning (Steve Morris, The Guardian).