Aelian, Varia Historia:

The Spartans were most economical with time, saving it for urgent matters in every way possible and not allowing any citizen to be idle or careless in using it, so that it should not be spent on aims outside the scope of virtuous action and so be wasted to no purpose.

Among other proofs of their principle is the following. The ephors heard that the Spartans who had captured Decelea (1) were taking a walk in the afternoon, and sent them the order “Do not go for walks [μὴ περιπατεῖτε]” because they were indulging in a luxury instead of training their bodies.

The Spartans were obliged to maintain their health not by walking but by gymnastic exercises.

(II 5)

(1) Dekelea war eine attische Festung nördlich von Athen, die von den Spartanern während des Peloponnesischen Krieges (413 v.u.Z.) erobert worden war und seitdem Athen bedrohte.