What is really in my control according to the Stoics?

Epictetus opens the Handbook with a division he treats as the foundation of everything else he teaches: some things are up to us, and some things are not. What is up to us is narrower than it sounds. It is not your body, your career, your relationships, or how things turn out. It is opinion, pursuit, desire, aversion, and in a word, whatever are our own actions (Handbook 1). Everything else, including body, property, reputation, and command, belongs to the category of things not in our control.

The common misreading treats this as a stress management trick: focus on what you can influence, let go of the rest, and you will feel calmer. That is not quite what Epictetus is claiming. He is not describing degrees of influence. He is making a claim about identity and value. The things that are up to us are by nature free and unrestrained. The things that are not are, in his word, slavish, dependent on circumstance, other people, or chance (Handbook 1). If you mistake something slavish for something free, something that belongs to others for something that belongs to you, the result is not mild inconvenience. It is disturbance: you will lament, find fault with gods and men, and be hindered in the deepest sense (Handbook 1).

So the real content of the claim is this: your judgments and your actions are the only things that are truly yours, because nothing external can reach in and take them from you. Your body can be restrained, your property taken, your reputation ruined. But how you judge what happens to you, and what you choose to do about it, cannot be touched by anyone else. Epictetus calls this the faculty that examines itself and everything else, the rational faculty, which alone can judge appearances rather than simply have them (Discourses I.1). Later in the Handbook he gives it a name: your own is only your reaction to how things appear, your prohairesis or faculty of choice (Handbook 6). This is the seat of good and bad for a person, not health or wealth or the opinions others form of you.

This has a sharp practical consequence that Epictetus does not soften. He tells you to totally suppress desire for anything not in your control, because desiring what you cannot secure guarantees disappointment, and to move your aversion away from sickness, death, and poverty, onto the one thing you can actually govern: whether your own faculties act in accordance with nature (Handbook 2). That is a demanding instruction. It asks you to stop wanting your health, your career, or other people's good opinion as though your happiness depended on securing them, not because those things are worthless, but because wanting them as though they were yours to guarantee sets you up to be hindered, disappointed, or wretched.

What changes for someone who takes this seriously is where they locate the argument. Marcus Aurelius makes the same point about the self: strip away the flesh and the breath, what is left is the ruling part, and that is what a person really is (Meditations 2.2). If your good is lodged in your judgments and actions rather than in outcomes, then no one can compel you against your will, and no one can, in the sense that matters, harm you (Handbook 1). Epictetus is explicit that this is not a claim you can hold halfway. If you want the great things, freedom and happiness, alongside power and riches, you will fail to get either, because pursuing both means aiming at goods that pull in opposite directions (Handbook 1).

One concrete practice follows directly from this. When something happens that strikes you hard, whether a slight, a loss, or bad news, ask a first question before any other: does this concern something that is up to me, my own judgment and action, or something that is not? If it is not, Epictetus's instruction is blunt: it is nothing to you (Handbook 1). That is not a call to feel nothing. It is a call to stop assigning your good or your harm to something that was never yours to control in the first place.