πολλάκις δοκεῖ τὸ φυλάξαι τἀγαθὰ τοῦ κτήσασθαι χαλεπώτερον εἶναι → it often proves harder to keep than to win prosperity | it is often harder for men to keep the good they have, than it was to obtain it
obstinately: Ar. and P. αὐθάδως; see also boldly.
zealously: P. and V. προθύμως.