“There is no vice which lacks a defense, none that at the outset isn’t modest and easily intervened—but after this the trouble spreads widely. If you allow it to get started you won’t be able to control when it stops. Every emotion is at first weak. Later it rouses itself and gathers strength as it moves along—it’s easier to slow it down than to supplant it.”

Seneca, Moral Letters, via The Daily Stoic (Page 175)