The Handbook of Epictitus
From What Did you Expect?
The Handbook of Epictitus, Chapter 4
When you are going about any action, remind yourself what nature the action is. If you are going to bathe, picture to yourself the things which usually happen in the bath: some people splash the water, some push, some use abusive language, and others steal. Thus you will more safely go about this action if you say to yourself, “I will now go bathe, and keep my own mind in a state conformable to nature.” And in the same manner with regard to every other action. For thus, if any hindrance arises in bathing, you will have it ready to say, “It was not only to bathe that I desired, but to keep my mind in a state conformable to nature; and I will not keep it if I am bothered at things that happen.
The complete text of The Handbook of Epictitus