Carpe diem. Marcus Aurelius 2.4

Marcus reminds himself that mortal life is short. Act while you can, or the moment for action will pass. Don't put off forever the tasks that really matter to you. You can hear the Greek <here>.

Μέμνησο ἐκ πόσου ταῦτα ἀναβάλλῃ καὶ ὁποσάκις προθεσμίας λαβὼν παρὰ τῶν θεῶν οὐ χρᾷ αὐταῖς. δεῖ δὲ ἤδη ποτὲ αἰσθέσθαι τίνος κόσμου μέρος εἶ καὶ τίνος διοικοῦντος τὸν κόσμον ἀπόρροια ὑπέστης καὶ ὅτι ὅρος ἐστί σοι περιγεγραμμένος τοῦ χρόνου, ᾧ ἐὰν εἰς τὸ ἀπαιθριάσαι μὴ χρήσῃ, οἰχήσεται καὶ οἰχήσῃ καὶ αὖθις οὐκ ἐξέσται.

Remember how often you have put these things off, how many times you have set a date with the gods only to leave them standing. You must now see the order of which you are part, acknowledge the ruler of that order whose shadow you are, and make peace with the fact that the boundary of your time is set. If you do not venture forth to seize the moment now, under the open air, it shall pass, and you shall pass, and never will you meet it again.