When I am standing or walking, and thinking about something other than my posture, I exhibit a bit of lumbar hyperlordosis, a fair amount of thoracic kyphosis and a bit of forward head (both my professional and avocational pursuits involve computer use).
For about 18 months I have been working out regularly and working on stretching the hip flexors, strengthening the core, the glutes, rows, etc.
When I look in the mirror, I can engage the abdominus rectus, thrust a bit with the glutes, and put my chest up and I see a very good-looking posture. However, when I am not thinking about it (which is 99% of the time) I regress.
I do have a standing/sitting (up/down) desk, but when I stand and I engage in a good posture consciously, then return to my work. Invariably some time later I notice that I have allowed my belly to protrude and am resting a bunch of weight on my lumbar spine. I then correct it.
In general, I find it easier to identify good vs. bad posture when standing vs. sitting, and when I am standing I can imitate a person who has good posture for brief periods of time. But when I am sitting, I am less clear on what I am doing vs. what I should be doing, and how bad it actually is.
My question is in two parts:
1) Do people who exhibit great posture have to think about it?
2) How does sitting posture relate to standing posture? In particular, what types of sitting posture mistakes contribute to lumbar hyper lordosis, thoracic kyphosis and forward head when standing?