Cito rumpes arcum si habueris semper tensum, at si laxaris erit utilis cum voles
[You will soon break the bow if you keep it always stretched, but if you slacken it, it will be fit for use when you wish.]

Phaedrus (15 BC-AD 50) Roman fabulist, poet

Fables, Book 3, #14, “Aesop Playing”