Why do you place your mental well-being in the hands of others?

Donald's Commentary on The Handbook of Epictetus #28

If someone handed over your body to any person who met you, you would be vexed; but that you hand over your mind to any person that comes along, so that, if he reviles you, it is disturbed and troubled – are you not ashamed of that?

Commentary

When we’re overly-concerned about insults, our reputation, or what others think of us in general, Epictetus says we’re handing over our minds to them. For the Stoics, this is a form of slavery to our own passions and to externals. Others have power over us, ultimately, if we care too much about our property or reputation, because these are never entirely under our control, and they are often, at least in part, under the control of other people — meaning that others always have “leverage” over someone who invests unconditional value in external goods.