Wiktionary
self-mastery
n. The conscious control of one's behaviour; self-command.
Usage examples of "self-mastery".
In dock areas I found the packing houses, seeking to investigate perspectives pure as theorems, the self-mastery of these concrete structures, invulnerable to melancholy.
Any man endowed with Rafe's monumental degree of arrogant self-mastery would naturally be chagrined by the condescending assumption that he did not have complete control of his psychic talent.