Labour to keep alive in your breast that little spark of celestial fire,—conscience.

Conscience is not a fixed instrument; it gets duller with disuse and sharper with attention. Every time you override it in a small matter, the next override is easier, and after enough of them the signal stops arriving at all. The danger is not a dramatic fall but a gradual loss of the ability to feel that something is wrong. Keeping it alive is active work rather than a natural state.

Notice the next small thing you are talking yourself out of minding, and mind it. Say the correction, refuse the shortcut, admit the error nobody caught. The size of the matter is not the point; the practice is.