διαγωνιστέον
From LSJ
εἰ γάρ κεν καὶ σμικρὸν ἐπὶ σμικρῷ καταθεῖο καὶ θαμὰ τοῦτ᾽ ἔρδοις, τάχα κεν μέγα καὶ τὸ γένοιτο → for if you add only a little to a little and do this often, soon that little will become great (Hesiod W&D, 361-362)
English (LSJ)
A one must make a great effort, Ph.2.471.
Greek (Liddell-Scott)
διαγωνιστέον: ῥημ. ἐπίθ., πρέπει τις ἰσχυρῶς νὰ προσπαθήσῃ, Φίλων 2. 471.
Spanish (DGE)
1 hay que esforzarse Ph.2.471, Dsc.Ther.p.55, c. inf. σπουδαστέον καὶ δ. ... φυλάττειν Mac.Aeg.Ep.magn.245.6.
2 hay que combatir τούτους Procl.Theol.Plat.1.33.13.