When you are going about any action, remind yourself of its nature. Picture to yourself the things which usually happen in that action. Be prepared. Then, keep your own mind in an adequate state. For thus, if any hindrance arises, you will say, “It was not only to do this action that I desired, but to keep my mind in a state I decided; and I shall keep it only if I allow no thing to bother me.”
— Epictetus, (55-135 ce) Greek philosopher of the stoic school