In the recent issue of Readers Digest Asia, a man shared his story of suffering from a spinal injury resulting from a habit of sitting in uncomfortable positions for long hours as part of his work as a writer.
I think it is in the same issue (or the previous one) that people are advised to set their timers every 30 minutes to remind them to look away from whatever it is they're doing (working on the computer, watching a movie on their LCD TV, drafting, etc.) so that the eyes can get a reprieve and be better able to focus.
And movement also begets movement, bowel movement that is. Even the healthiest of food is all about getting our heart pumping, our bladders emptying, our stomachs digesting.
So safeguarding one's health is really a matter of movement. Activity. Make sure you have enough in your life lest you damage your body in ways that are irreparable.