How does Marcus Aurelius say we should relate to our own opinions to avoid pain?

Marcus does not say pain is fake, or that you should pretend it away. He says something more precise: the security you are looking for does not come from removing the painful thing, it comes from removing the opinion you have attached to it. Take away your opinion about that which appears to give you pain, and you yourself stand in perfect security (Meditations 8.40). He then asks who this "you" is that stands secure, and answers his own question: the reason (Meditations 8.40). The self that can be secure is not your body, your reputation, or your circumstances. It is your capacity to judge.

The common misreading treats this as a trick for suppressing feeling: grit your teeth, tell yourself it doesn't hurt, move on. That is not what Marcus is doing. He is not asking you to deny a sensation. He is pointing at the extra layer most people add without noticing, the judgment that says this is bad, this should not be happening, this is a disaster. Strip away that added judgment and what is left is the bare event, which by itself cannot touch the one part of you that is actually yours: your faculty of reason, your capacity to assent or withhold assent.

This fits a claim Marcus makes elsewhere about how little external events can do to you. Things like death, life, honor, dishonor, pain and pleasure happen equally to good people and bad people, and so cannot themselves be what makes a life good or bad (Meditations 2.11). If pain fell only on the wicked and never on the just, you might call it an evil in the strict sense. Since it falls on everyone regardless of character, it cannot be the thing that makes a person worse. What makes a person worse is the false judgment that pain is a catastrophe, a judgment that then drags fear, resentment, and despair along with it.

This is a hard claim to sit with, because pain is not an illusion. A sprained ankle before a match still hurts. Marcus is not asking you to feel nothing. He is asking you to notice that on top of the raw sensation, you have added a story: this ruins everything, this should not be happening to me. That story is the part that is up to you, and it is the part doing most of the damage. The sensation passes through you. The opinion is the piece you keep feeding.

What changes for someone who takes this seriously is where they put their attention when something hurts. Instead of asking how to make the pain stop, they ask a different question: what am I telling myself about this pain right now, and is that judgment true. Often the honest answer is no. The judgment is an inference, a habit, an old fear dressed up as a fact. Once you see it as a judgment rather than a report of reality, you have somewhere to stand that the pain itself cannot reach: your reason, which is yours in a way nothing external ever is.

The concrete practice is small and repeatable. The next time you notice pain, physical or otherwise, pause before reacting and separate two things out loud, even silently: this is what is happening, and this is what I am telling myself about it. Question the second part. You will not always be able to drop the opinion instantly, and Marcus does not promise that. But you will see, more clearly each time, that the opinion was never forced on you. It was added. And what was added can be taken away.