Protect your mind
Principle 28 from the Enchiridion
Keep what is useful and let the rest go. Do not give a stranger's comment more space in your mind than it deserves.
Original Passage
If a person gave your body to any stranger he met on his way, you would certainly be angry. And do you feel no shame in handing over your own mind to be confused and mystified by anyone who happens to verbally attack you?
Modern Interpretation
Epictetus asks why we protect the body so carefully while allowing a stranger's comment to occupy the mind for hours.
Our attention is our responsibility. If one remark takes over the whole day, we have given that person far too much space in our head. That does not mean becoming numb. Listen, judge what was said, and decide what deserves to stay. Useful criticism can be kept. An empty attack can be left where it came from.
In Practice
A common version of this is easy to recognize. Someone you barely know makes a harsh comment, and you replay it all day. Your work suffers because half your attention is still arguing with them.
Ask whether the comment deserves this much space. Take whatever is useful, leave the rest, and return to what you were doing.
Reflection Question
Whose words have been living in your head lately? Do they really deserve that much room?