Plato, Laws 789c

δὴ δέουσιν ἡγεῖσθαι τοὺς πόνους αὐτοῖς εἶναι τοὺς πρὸς ἄλληλα μετρίους, ἐν οἷς αὐτὰ ἀνακινοῦσι γυμνάζοντες· πρὸς γὰρ τούτοις λαβόντες ὑπὸ μάλης ἕκαστος, τοὺς μὲν ἐλάττονας εἰς τὰς χεῖρας, μείζους δʼ ὑπὸ τὴν ἀγκάλην ἐντός, πορεύονται περιπατοῦντες σταδίους παμπόλλους ἕνεκα τῆς εὐεξίας οὔτι τῆς τῶν αὑτῶν σωμάτων, ἀλλὰ τῆς τούτων τῶν θρεμμάτων, καὶ τό γε τοσοῦτον δηλοῦσι τῷ δυναμένῳ καταμαθεῖν,

But they are far from thinking that the training they give them by exciting their pugnacity provides sufficient exercise; in addition to this, each man takes up his bird and keeps it tucked away in his fist, if it is small, or under his arm, if it is large, and in this way they walk many a long mile in order to improve the condition, not of their own bodies, but of these creatures. Thus clearly do they show to any observant person that all bodies benefit, as by a tonic, when they are moved by any kind of shaking or motion,