If thou art pained by any external thing, it is not this thing that disturbs thee, but thy own judgement about it. And it is in thy power to wipe out this judgement now.

This is the Stoic distinction between events and the judgements we add to them, in the form Marcus gave it to himself. The point is not that nothing hurts, but that the part of the pain that comes from our opinion can be revised. The wording is George Long’s 1862 translation, which is in the public domain; modern translations phrase it differently.