Your desk chair might be a mortal enemy. Same with your driver's seat or your La-Z-Boy. It's not so much the size or shape of your perch -- it's all about how long you sit on it.

When researchers looked at how much sitting people did over 12 years, they found that people whose butts met chairs for most of the time, most of their days, died sooner and with more pain than people who moved around. Even if they also exercised for 30 minutes every day, chair dwellers couldn't bring their mortality rate down to the level of someone who sat for only a quarter of the day.

You can, however, unseat this killer! If you live at your desk, at least get up and walk around frequently. It also keeps your head clear, and you never know what you'll see or learn (about office gossip or about actual work -- innovations may pop into your head as you see your colleagues).

And keep working out. Exercise does get you ahead. Among people who sat for the same percentage of time each day, active people (read exercisers) lived longer and with less disability than inactive folks. Don't just bump up how long you're at the gym; also aim to be more active when you're not there. Doing tortilla-chip curls (moving your hand from chip bowl to mouth) or moving from dining-room chair to Barcalounger doesn't count. We're talking gardening, walking the dog, or playing freeze tag with your kids (or someone else's). The equation is simple: Watch less, play more, live more.