Highlights from The Enchiridion written by Epictetus.
There are things which are within our power, and there are things which are beyond our power. Within our power are opinion, aim, desire, aversion, and, in one word, whatever affairs are our own. Beyond our power are body, property, reputation, office, and, in one word, whatever are not properly our own affairs.
If you attribute freedom to things by nature dependent and take what belongs to others for your own, you will be hindered, you will lament, you will be disturbed.
You take for your own only that which is your own and view what belongs to others just as it really is, then no one will ever compel you, no one will restrict you; you will find fault with no one, you will accuse no one, you will do nothing against your will; no one will hurt you, you will not have an enemy, nor will you suffer any harm.