Clients often tell me they're working on their posture. I'm a massage therapist, right? I'm supposed to approve of people minding their alignment: sitting in perfect, harmonious balance, with their arms in the exact neutral position. So they're surprised, possibly a little hurt, when I say, “There's nothing wrong with your posture. Forget about it.”
I'm rather abrupt because 1) worrying about your posture ups your stress and will tend to make the problem worse, 2) people virtually never change their posture, whether they worry about it or not, and 3) it draws energy and attention away from the real problem. The problem is not how you're sitting, the problem is how much you're sitting. And the answer is to get the hell out of the chair and do something, whenever you can. Really get up, and move around. Go jog around the parking lot a couple times. Lie down on the floor for five minutes, pulling your knees up to your chest a couple times. Waggle and twist.
If your workplace culture frowns on this, then shame on them. But do whatever you have to do. Sneak out to the stairwell. Jog in a bathroom stall. Slip out to your car and lie down in the back seat: if someone sees you, pretend you're looking for your phone. Whatever. No amount of exquisitely balancing your head on your neck, and centering your rib cage above your pelvis, and positioning your arms on or off the arms of the chair, is going to change the fact that sitting for even a few hours doing desk work is damned bad for you, and that sitting for nine or ten hours is even worse. If you're doing that, and then going home and spending five more hours doing the same, as your leisure relaxation, then God help you.
A stand up desk won't help much either. Even one that adjusts so you can either sit or stand probably won't make a lot of difference. Again: it's not how you do it, it's the fact that you are doing it. To work with a screen and keyboard means that you're holding most of your body rigid while you do fine motor work with your eyes and fingers. Doing this for hours at a time makes demands on your body that it's not designed to meet. The problem is not your alignment, or your level of enlightenment, or your emotional maturity: it's that you're stressing your body beyond its design tolerances.
Most corporate ergonomic interventions begin with the assumption that a person should be able to sit doing deskwork for forty or fifty hours per week: companies that employ people to do it are understandably reluctant to question this assumption. But if you want a nice long working life with a happy neck and back, you had better question it. I see people every week whose neck and back pain has rendered them unable to work. Young people, some of them: thirty- and forty-year-olds. Don't join them. Get out of the chair and away from the desk.
Massage is wonderful. I highly recommend it. And it will even help somewhat. But there's no way that even twice-weekly massage – more than most people can afford – will offset what a day spent mostly at deskwork is going to do to you. You need to get serious: realize that you're challenging your body to do something very difficult for it, and bring your ingenuity to bear on mitigating and relieving its hardships.
Feldenkrais-trained Todd Hargrove's wonderful set of posts on posture.
A great essay on sedentary workplace survival: Paul Ingraham's piece on “microbreaking."