And to add to that, I use to work at an office that had an ergonomics specialist on staff. The thing that stuck with me she said even though there are some general things you can do to improve RSIs and back pain, "it's not about a single perfect position or chair, it's about changing your setup constantly" - change your chair height, arm eight, lumbar position, even chairs entirely, never stay in the same position day in day out. it's the repetition of singular stresses that wear out that weak link in your body.
I am pretty sure I have some kind of sciatica, but I do yoga with my wife, I lift weights, I do core and stamina training... I have lost over 30lbs in the last year and it has improved my back pain dramatically. But there's still only so much you can do when you sit all day, and I am literally wearing out my current chair, so it's time for an upgrade.
I also get up at least 2x an hour, I am easily distracted, so that's nice. Ironically I never had back pain when I was a smoker because of all the breaks I took. But all other aspects of my life have also improved dramatically since I quit, so it's a fair trade.
