William James on habit is a key read here, I think: https://en.wikisource.org/wiki/Habit_(James_1914)
> Plasticity … in the wide sense of the word, means the possession of a structure weak enough to yield to an influence, but strong enough not to yield all at once.
> Any sequence of mental action which has been frequently repeated tends to perpetuate itself; so that we find ourselves automatically prompted to think, feel, or do what we have been before accustomed to think, feel, or do, under like circumstances, without any consciously formed purpose, or anticipation of results.
> Habit is thus the enormous fly-wheel of society, its most precious conservative agent. It alone is what keeps us all within the bounds of ordinance, and saves the children of fortune from the envious uprisings of the poor. It alone prevents the hardest and most repulsive walks of life from being deserted by those brought up to tread therein. It keeps the fisherman and the deck-hand at sea through the winter; it holds the miner in his darkness, and nails the countryman to his log cabin and his lonely farm through all the months of snow; it protects us from invasion by the natives of the desert and the frozen zone. It dooms us all to fight out the battle of life upon the lines of our nurture or our early choice, and to make the best of a pursuit that disagrees, because there is no other for which we are fitted, and it is too late to begin again. It keeps different social strata from mixing. Already at the age of twenty-five you see the professional mannerism settling down on the young commercial traveller, on the young doctor, on the young minister, on the young counsellor-at-law. You see the little lines of cleavage running through the character, the tricks of thought, the prejudices, the ways of the ‘shop,’ in a word, from which the man can by-and-by no more escape than his coat-sleeve can suddenly fall into a new set of folds.
On the whole, it is best he should not escape.
And this doomerism:
> It is well for the world that in most of us, by the age of thirty, the character has set like plaster, and will never soften again.