Both of those really hit home atm. I have been doing Silat, an Indonesian martial art, for the past 8 years. So much of it is "non-explained movement". I was very lucky in that my guru badgered his teacher with "silly questions" and so he has a completely different mental map of this thing that we do than most other instructors I've seen.
And that map is _absolutely_ body-centric. Unfortunately, our culture lets the kids who "show competence" receive all the physical training, while the rest of us have to struggle through retraining ourselves later (if we ever take that opportunity). Reconnecting with the body means undoing a huge amount of chronic tension (your pose-hold-relax-repeat description has deep parallels to Christopher Hyatt's "Undoing Exercises"... who I think has Gurdjieff connections). Then looking past the flood of sensory information coming in from the "environment" and focusing on the sensory information coming from "inside".
Our beginner breathing meditations involve flowing the arms and hands all across the body, almost like you are lathering yourself with soap in the shower. This is SUPER WEIRD FEELING at first, almost indescribably weird. You are not socialized to touch yourself like this (you are basically anti-socialized away from it), you fuck up and lock up, or your breathing catches and gets blocked, or your hand leaves contact with the body. Your "monkey brain" is going to jump all over these feelings and try to convince you that this weird stuff you are doing is boring, not worth your time, etc. The best I can recommend is to just return focus to the breath, the intellect will run out of steam eventually.
The point to our exercise is to retrain the body to be confident that it can move in certain ways (through certain vectors) with power. We are literally "filling in the blank spots on our personal-space map". But guru Brandt and I just made that metaphor up to distract the intellect.

Will go back and re-read this thread. Thanks for posting.