"We have said that it is absolutely necessary to give one's mind to God, that the most dangerous struggles are those of the mind, that tepidity of life has its source in sloth and indecision in choosing God and rejecting evil. We have said that, at once and unhesitatingly, thoughts that have even the appearance [...]
"If you take not my word for this marvelous virtue (penance/mortification), try it yourselves, for a time, at least; and when you shall have had a taste of it, ah! you will not give it up. You must become convinced of it, enthusiastic over it, for to do anything well, to arrive at the possession [...]
"There are two ways of honoring Our Lord by penance; the one is inspired by negative love, the other by positive love. By the first, we prevent evil or we correct it. It is necessary, but it makes us act only through the strict duty of Christian justice. For the practice of this kind of [...]
"Contentment, therefore, comes in part from faith – that is, from knowing the purpose of life and being assured that whatever the trials are, they come from the hand of a loving Father. Secondly, in order to have contentment one must also have a good conscious. If the inner self is unhappy because of moral [...]
"True, it is hard, and there are few who persevere in it and become saints. They mortify themselves for a time while the passions are still to be feared; and when peace reigns they cease to do so. From this it comes that there are so many of merely ordinary virtue, and that they never [...]
"Our enjoyment of life is vastly increased if we follow the spiritual injunction to bring some mortification and self-denial into our lives." Source: Ven. Fulton J. Sheen, Way to Happiness, St. Pauls, 1998.
That all possible kinds of mortification, if they were void of the love of God, could not efface a single sin. Source: Brother Lawrence, The Practice of the Presence of God and The Spiritual Maxims