There is only one way to happiness and that is to cease worrying about things which are beyond the power or our will.

The saying distills a central Stoic doctrine associated with Epictetus: tranquility comes from distinguishing what is “up to us” (our judgments, choices, and actions) from what is not (other people, chance, reputation, illness, outcomes). Worry is portrayed as misdirected attention—an attempt to control externals that lie outside the will. By withdrawing emotional investment from uncontrollable events and focusing effort on one’s own moral purpose, a person gains steadiness and freedom from anxiety. The “one way” is rhetorical emphasis: happiness is not found by mastering the world, but by mastering one’s responses to it.

1) “There is only one way to happiness and that is to cease worrying about things which are beyond the power of our will.”
2) “Happiness and freedom begin with a clear understanding of one principle: some things are within our control, and some things are not.”
3) “Make the best use of what is in your power, and take the rest as it happens.”