ἐνσπουδάζω
From LSJ
Τὸ νικᾶν αὐτὸν αὑτὸν πασῶν νικῶν πρώτη τε καὶ ἀρίστη. Τὸ δὲ ἡττᾶσθαι αὐτὸν ὑφ' ἑαυτοῦ πάντων αἴσχιστόν τε ἅμα καὶ κάκιστον. → Τo conquer yourself is the first and best victory of all, while to be conquered by yourself is of all the most shameful as well as evil
English (LSJ)
A employ oneself actively in, τῇ Σμύρνῃ Philostr.VS1.25.2,al.; πόλις ἐνσπουδάσαι ἀγαθή Lib.Or.11.268.