Enchiridion · §34

ὅταν ἡδονῆς τινος φαντασίαν λάβῃς, καθάπερ ἐπὶ τῶν ἄλλων, φύλασσε σαυτὸν μὴ συναρπασθῆναι ὑπ᾽ αὐτῆς· ἀλλ᾽ ἐπανάμεινόν σε τὸ πρᾶγμα καὶ ἀνάλαβέ τι διάστημα. εἶτα μνήσθητι ἀμφοτέρων τῶν χρόνων, ἔν τε ᾧ ἀπολαύσεις τῆς ἡδονῆς, καὶ ἐν ᾧ ἀπολαύσας ὕστερον μετανοήσεις καὶ αὐτὸς σεαυτῷ λοιδορήσῃ.

hotan hēdonēs tinos phantasian labēs, kathaper epi tōn allōn, phulasse sauton mē sunarpasthēnai hup' autēs; all' epanameinon se to pragma kai analabe ti diastēma. eita mnēsthēti amphoterōn tōn chronōn, en te hō apolausis tēs hēdonēs, kai en hō apolausas husteron metanoēseis.

When a pleasurable impression presents itself to you, guard yourself against being carried away by it, just as you would with any other impression. Let the thing wait, and give yourself an interval. Then call to mind both moments: the time during which you will enjoy the pleasure, and the time afterward — when you will regret it and condemn yourself.

— Enchiridion 34

Source: Greek (Schenkl/Oldfather critical edition tradition) + Long 1877 English translation