You can only truly master one thing, according to Epictetus

"Some things are up to us and some are not. Up to us are judgment, inclination, desire, aversion - in short, whatever is our own doing. Not up to us are our bodies, possessions, reputations, public offices - in short, whatever is not our own doing. He then proceeds to tell us that a good life is one in which we focus on the things that are up to us while, at the same time, striving to develop an attitude of acceptance and equanimity for the things that are not up to us."

"If this sounds familiar, it may be because Epictetus's manual was used as a source of spiritual exercises by Christian monks throughout the Middle Ages, and in the early 1930s, American theologian Reinhold Niebuhr echoed the philosopher's ideas about control in his 'Serenity Prayer,' which is often recited at the beginning of meetings for Alcoholics Anonymous and other 12-step organizations: 'God, grant me the serenity to accept the things I cannot change, the courage to change the things I can, and the wisdom to know the difference.'"

"Epictetus says only one thing is truly up to us: our deliberate, conscious judgments."

Mastery often implies deep skill and control, but absolute control is limited. Only certain internal states are within personal control: judgment, inclination, desire, and aversion—what constitutes one’s own actions. External things such as the body, possessions, reputation, and public office lie outside personal control. A good life directs effort toward governing what is up to the individual while cultivating acceptance and equanimity toward what is not. This distinction influenced Christian monastic practice and later informed formulations like the Serenity Prayer. Deliberate, conscious judgments serve as the primary locus of true agency.

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