Correcting posture requires not only a strengthening and lengthing of the correct muscles, but literally a new perception of what your body is doing. Bring strong and flexible is sufficient to walk.
I sometimes indicate how hard this is as “learning to walk again”. Retraining your posture is on the order of difficulty of learning to walk for the first time. Imagine how much effort and attention you put into that the first time around.
Normal human beings put 0 effort and attention into walking.
They stumble about until it works. A toddler learns to walk before they have most of their conscious brain development.
