The true penance comes when God takes away the soul's health and strength for doing penance. Even though I have mentioned elsewhere the great pain this lack causes, the pain is much more intense here. All these things must come to the soul from its roots, from where it is planted.
Teresa of AvilaKeep this in mind, for it is very important advice, so do not neglect it until you find you have such a fixed determination not to offend the Lord that you would rather lose a thousand lives and be persecuted by the whole world, than commit one mortal sin, and until you are most careful not to commit venial sins.
Teresa of Avila