There was a cartoon I saw recently. Two guys are standing outside the Pearly Gates; one says to the other, "In the end, it really did just come down to posture."
There seems to be a lot of psychology in this node thus far. Perhaps a bit of practical advice would come in handy.
If, like me, you consider Heaven or Hell just what you make out of this one life you get on Earth, then Heaven would probably include being free of physical pain. I can tell you from personal experience that bad posture throughout a lifetime will result in plenty of pain when you get older. In my case, it's the rounded shoulder posture from sitting in front of a desk for years and years. The only thing worse than typing for hours is filling out paperwork which also adds the bending over problem to the rounded shoulders. No one really stressed good posture when I was a kid, but I sure wish they had. I now spend a large portion of my days trying to stretch the muscles in my neck and get the knots out of the shoulder blade areas.
Am I a candidate for this grim future? you might ask. Well, try this: Pull your shoulder blades together and sit up as straight as you can. Now swivel your head as far to the left as you can. Do you feel a pulling on the right side of your neck? Now nod your chin down as far as you can. Did it feel as if you were about to snap something? Now do the same turning to the right.
Oh no! What can I do? Well, first of all, you should realize that aside from loading trucks all day for a living, the worst thing for your back is sitting. So get off your ass every 15 minutes or so and do something else; preferably something that involves stretching. There are many techniques for stretching, tai chi, yoga, etc. But the hardest part, as you well know, is the "getting off your ass" part. You've got to finish that last bit of code or respond to that last/msg or see if that girl will actually be able to. . . well, you know what I mean. They sell standing and even walking desks where you do your work standing or on a treadmill going at a very slow pace. These both sound like great ideas, but reviews on the internet are mixed.
Maybe the best way to help you solve the problem would be to understand why it's happening; and I don't mean psychologically. Your head weighs about the same as a bowling ball. Go find something that weighs 12-13 lbs. Yes, I mean right now! Now stand up and hold this thing out in front of your chest about a foot. See how long you can hold it there. Now pull the object into your chest and see how much less tension there is on your neck and upper back. When you walk or sit stooped over, your head represents this object and that's how much pressure you're putting on yourself to hold it like that all day. Try to get your head directly above your spine and keep it there. See how your shoulder blades naturally go to a neutral position when you do? Now, hold your head correctly, push your butt as far back in your chair as you can, and constrict your anus 100 times. You can thank me when you retire.