As the body is to be chastised at the beginning so that sin may not reign in it and we may overcome temptations, so too when the temptations have been overcome we must persevere in the same practices not only for fear of falling back but also out of desire for progress.
Thus through the mortification of the flesh the spirit may thrive the better and, the lighter and more slender the fetters which attach it, the more freely it may rise to spiritual things.
Blessed Guerric of Igny
Liturgical Sermons