During this Lent we must truly seek with greater fervor that which is not just a part but is the entire mystery of this whole season. Therefore if perhaps your zeal has somewhat abated during recent days, it is fitting that you rekindle your fervor of spirit. If only the belly has sinned, let it alone fast, and that will be enough; but if other members have also sinned, why should they not fast as well? Let the eye fast, since it has ravaged the soul. Let the ear fast, the tongue, the hand, even the soul itself. Let the eye fast from curious glances and from all wantonness, that when well-humbled it may be brought to repentance, the eye that while free wandered wickedly into sin. Let the ear fast that itches for tales and rumors and whatever is idle and of no use for salvation. Let the tongue fast from slander and grumbling, from fruitless, vain, and scurrilous words, and sometimes, too, because of the importance of silence, even from the very things that seem necessary. Let the hand fast from making useless signs and from all work not explicitly commanded. But also, and much more, let the soul itself fast from vices and from its own will. Without this kind of fast all the rest is disagreeable to the Lord. As it is written, on your fast days you do what you want!
Bernard of Clairvaux, Sermons for Lent and the Easter Season, Lent – Sermon Three: Of Devotion and Fervor in Fasting, verse 4 (CF 52, page 38)