Act as a Dying Person

Let each thing you would do, say, or intend, be like that of a dying person.

Meditations, Book 2

Related quotes.

Don't explain your philosophy. Embody it.

Enchiridion, Chapter 46

Don't just say you have read books. Show that through them you have learned to think better.

Discourses

First say to yourself what you would be; and then do what you have to do.

Discourses, Book 3