If you are distressed by anything external, the pain is not due to the thing itself, but to your estimate of it; and this you have the power to revoke at any moment.
What Marcus Aurelius captures here goes beyond the tired self-help notion that you should "just think positive"—he's pointing out that your judgment itself is the actual problem, not your circumstances. The Stoic insight is that between event and suffering sits your faculty of assent, that quiet moment where you agree something matters terribly, and you can refuse that agreement. When your boss criticizes a project, the sting isn't the words themselves but your internal verdict that this means you're incompetent; revoke that verdict, and the sting vanishes, leaving only information to act on. This matters because it places agency exactly where you actually have it: not in controlling what happens, but in controlling what you decide it means.
“Never let the future disturb you. You will meet it, if you have to, with the same weapons of reason...”
Marcus Aurelius“For every minute you are angry you lose sixty seconds of happiness.”
Ralph Waldo Emerson“Between stimulus and response there is a space. In that space is our power to choose our response. I...”
Viktor Frankl“We suffer more often in imagination than in reality.”
Seneca