I haven't gone outside for about 5 hours. That can't be healthy. Anyway, while you're tethering yourself to your computer to many hours a day, you might as well use the best materials and exercises to keep yourself posture-perfect and ergonomically correct.

In terms of finding a good office chair, it seems like you get what you pay for: however, there are used office supply stores so you could actually get what somebody else originally paid for. (Or you can see if somebody is giving it away at FreeCycle.) Other suggestions here at Ask Metafilter.

As for repetitive stress disorder and ergonomics, there are tons of gadgets you can buy to soothe the angles of your body, including this laptop stand that lets you skate your laptop around your desktop if you like and as well as gesture shortcuts and fancy mouses. Plus there are footrests, techy chairs and ergonomic keyboards galore. There are also some programs you can use to save yourself the movement, like ActiveWords or Saft. Or, if you have a lot of time, you can always try wiring your typewriter to your computer.

If you don't have tons of money to spend, though, your best defense is learning proper posture (I just learned that I have bad wrist angles). On the other hand, you might prefer to drop money on desk accessories to save yourself from doing desk yoga and deskercizes.

If you have feedback on body-soothing tips and doohickeys you use at your work station, please send it in. I have received rave reviews on "The Quill" Mouse but want to hear more from you.