From discussions with my PT.
- He told me that you can hold a proper position for about 10 minutes, then you forget and go back to your usual slouch.
The only way to beat that is to pay attention and check yourself often enough that good posture becomes a habit, just like slouching became a habit. Easier said than done.
- You need to sit so that you are sitting on the bottom of the hip bone, not on your tail bone, so the spine is not curved back. If you rotate your hip and sit on the tail bone, like when you slouch, you are pulling your back out.
I found that the chair makes a BIG difference.
- If the pan of the chair can be tilted forward, it counters the slouch and helps keep your back straight.
- Another is to sit back into the chair, so that the backrest of the chair supports your lower back, so that you can't slouch. Slouching many times happens when there is no support for the lower back, so when you are not paying attention to your back, the back curves out.
- A 3rd is for chairs that you cannot adjust the pan angle, like when you are at a restaurant. Sit on the front of the pan, so that your thigh angles down. This makes it easier for those of us, with short ham string, to not rotate the hip bone.
Per the insurance guys that I used to work with, "back injury is cumulative." It is the result of all the years of bad treatment that one day, you bend to pick up a pencil from the floor, and your back gives out. It wasn't picking up the pencil that caused the back injury, that was just "the straw that broke the camels back."
And for those of you on the computer a lot, pay attention to your posture there.
It was my wife that caught me hunched over looking at my monitor. It seems that I position my head level with the middle of the screen. So with a low monitor, I lower my head and hunch my back. To counter that I now raise my monitor to get me to lift my head, and thus straighten my back. This rankled all the ergo people in the offices I worked at. They said my monitor was too high, and wanted to lower it down.