ἀσκητέον

From LSJ

τραχὺς ἐντεῦθεν μελάμπυγός τε τοῖς ἐχθροῖς ἅπασιν → he is a tough black-arse towards his enemies, he is a veritable Heracles towards his enemies

Source

Spanish (DGE)

1 hay que practicar τὴν σοφίαν Pl.Grg.487c, σωφροσύνην Pl.Grg.507d, τέχνην Gal.Adhort.14, τὴν μουσικήν Aristid.Quint.133.23, cf. X.Mem.2.1.28, Arist.Pol.1325a13
hay que ejercitar τοὺς πόδας X.Eq.4.3.
2 hay que entrenar πρὸς γὰρ τοὺς στρατιωτικοὺς ἀγῶνας τοὺς παῖδας ἀσκητέον Plu.2.8d
abs. hay que hacer ejercicio corporal Erot.19.16.