Many of us spend a good deal of time sitting at desks covered in keyboards, monitors and mice (of the computer variety). You may have trouble convincing your spouse otherwise, but there's a lot more than just sitting going on.
To create a good work environment, you don't want your chair too low. The higher it is, the less you'll have to bend to get in and out of it -- your knees and hips will thank you. If you're standing and working at a desk or counter, make sure you're not having to hunch over to write or type.
Take the time to arrange your workstation so you'll be comfortable in a variety of positions: typing on your keyboard, reading the screen with your hand on your mouse or writing on a desk surface. Make sure your elbows and forearms are comfortably supported, and that your thighs rest parallel to the ground (if it's more comfortable, it's also good to have your knees slightly higher than your hips, by using a footrest, for instance). It's important not to have a desk-and-chair combo that restricts your natural movement -- you should be able to rearrange your legs without bumping into the inside walls of the desk cavity. Your rear end should be pushed completely back into the chair.
Do all of this and your joints will be sitting pretty for years to come.