Meditations 4.17.1

Μὴ ὡς μύρια μέλλων ἔτη ζῆν. τὸ χρεὼν ἐπήρτηται· ἕως ζῇς, ἕως ἔξεστιν, ἀγαθὸς γενοῦ.

Do not live as though you had ten thousand years ahead. What must happen hangs over you. While you live, while you can, become good.