Of things some are in our power, and others are not. In our power are opinion, movement towards a thing, desire, aversion (turning from a thing); and in a word, whatever are our own acts. Not in our power are the body, property, reputation, offices (magisterial power), and in a word, whatever are not our own acts.
And the things in our power are by nature free, not subject to restraint nor hindrance: but the things not in our power are weak, slavish, subject to restraint, in the power of others. Remember then, that if you think the things which are by nature slavish to be free, and the things which are in the power of others to be your own, you will be hindered, you will lament, you will be disturbed, you will blame both gods and men. […]
The Stoic move is not to want less. It is to direct desire only at what is yours to give. Everything else — the body, the reputation, the position, the loved one's behaviour — is held with a hupexairesis, a reserve clause: valued but not depended on.
Epictetus, Enchiridion 1 · trans. George Long (1877)
Context
The opening of Epictetus' handbook, the Enchiridion, distilled by Arrian from the longer Discourses. The dichotomy here is not advice — it is the structural beam of the rest of Stoic practice. To get this wrong is to misread everything that follows.