How do we enlarge movement repertoire?

Two quotes. First quote by Eric Franklin, from his book Dynamic alignment through imagery:

Your head floats up and your body dangles easily from your head. If you prefer to use a metaphor, you can think of your head as a balloon and your body as the string hanging down from it.

If you imagine this vividly enough, if you really feel it, sense it, it might (quite immediately) free your neck from some tension. You might sit up or stand up easier, maybe you stand taller with more ease. You might walk easier, breath easier. Do you? Don’t you?

Second quote by Julian Jaynes, from his book The origin of consciousness in the breakdown of the bicameral mind:

It is by metaphor that language grows. The common reply to the question “what is it?” is, when the reply is difficult or the experience unique, “well, it is like —.”

Is it by metaphor that movement repertoire grows? Or is it by experimentation with movements, such as play? Or by introducing movement context? Or by introducing auxiliary movements? Or by breaking down a larger movement into smaller parts and practicing the smaller parts, replace broken parts with better ones, and then putting everything together again? Like cleaning the engine of a motorbike?

Example: Say you want to improve the turning the head, in standing. You would then observe that movement in a different position, for example while lying on the back instead of in standing. Or you add arm and shoulder movements to it. Or you restrict the head from moving and turn the body instead. In this way you would turn, for example, your shoulder girdle or your pelvis instead of your head. Or you would turn only your eyes instead of your head, and free your brain from some of that compulsory relationship between your eyes and your head (if any), thus freeing up your head movements, and possibly improving your breathing as well.

How do we incrementally and permanently improve movement quality? How do we enlarge movement repertoire? How is it that we replace bad movement habits with even worse ones? How would we replace them with better ones instead?

And why would we enlarge our movement repertoire? Obviously, after a stroke, when the movement repertoire has shrunken down considerably and many movements have to be learned again, almost as if from scratch. Or after an accident. Or after decades of sedentary lifestyle when we suddenly discover that we are stiff like a stick and can’t even sit down on the floor anymore. Improving one’s movement repertoire might also be something that might interest top performers, such as athletes or musicians. Or parents who would like their children to keep improving, instead of them becoming movement illiterate cellphone zombies.

I might argue that the way to improve one’s movement repertoire is through movement, as I described above. Imagery might be nice as well, so might be metaphors, as long as we come up with the images ourselves, I would imagine. Our own images, created from within, for our own movements, to act in this world.