Meditations 7.8.1

Τὰ μέλλοντα μὴ ταρασσέτω· ἥξεις γὰρ ἐπ’ αὐτά, ἐὰν δεήσῃ, φέρων τὸν αὐτὸν λόγον ᾧ νῦν πρὸς τὰ παρόντα χρᾷ.

Do not let the future disturb you. You will reach it, if you must, carrying the same reason you now use to deal with the present.