ἐξ ἑκουσίας
From LSJ
μέτρον γὰρ τοῦ βίου τὸ καλόν, οὐ τὸ τοῦ χρόνου μῆκος → for life's measure is its beauty not its length (Plutarch, Consolatio ad Apollonium 111.D.4)
Greek > English (Woodhouse)
Russian (Dvoretsky)
καθ' ἑκουσίαν Thuc. и ἐξ ἑκουσίας Soph. по собственной воле, добровольно.