If you take a very short body break every 30 minutes you will negate many of the injuries that can show up with years of poor posture.
I have previously talked about upper crossed syndrome, and this all ties together.
Are you sitting down?
The modern analogy that sitting is the new smoking is described in this Runners World summary. It explains that from a study in Australia that the accumilated hours/days spent sitting at work and home will lower your lifetime by a significant amount - similar to what smoking will do.
To me, this is a somewhat sensational approach to present the information. Sometimes it is unavoidable if your job involves a bit of sitting. It is what you do with your time away from sitting that is important. Can you walk to to the printer across the office? Can you park on the opposite end of the parking lot? Can you ride your bike to work? All simple and all possible. The other option is a stand-up desk - I recently purchased an affordable portable standing desk from Uncaged Ergonomics.
My take home message is this; if you need to sit, try to work on good posture and take many body breaks!