The harm incurred by the desire for willful joy in sensory goods.
In the first place, all the general kinds of harm that are born of other types of joy spring as well from this joy in sensory goods if it is not darkened and quelled through direction to God. These kinds of harm are, for example, obscurity of reason, lukewarmness, spiritual tedium, and so on. But in particular there are many kinds of harm, either spiritual or corporeal and sensory, which can be directly incurred through this joy.
First, through failure to deny joy in visible objects for the sake of going to God, the following evils result directly: vanity of spirit, mental distraction, inordinate covetousness, indecency, interior and exterior discomposure, impurity in thought, and envy. […]
Joy in the delights of food directly engenders gluttony and drunkenness, anger, discord, and lack of charity toward one’s neighbor and the poor, as toward Lazarus on the part of the rich man who ate sumptuously each day [Lk. 16:19-21]. Accordingly, there arise bodily disorders, infirmities, and impure movements from increasing lustful incentives. A decided spiritual torpor is directly engendered and the desire for spiritual things is so spoiled that one finds no satisfaction in them and is unable to discuss or take part in them. Distraction of the other senses and of the heart and discontent over many things also arise from this joy. […]
All these evils are caused by this kind of joy according to the intensity of the joy and also according to the disposition, weakness, or inconstancy of the individual. Some temperaments receive more detriment from one small occasion than others do from many.
Saint John of the Cross
The Ascent of Mount Carmel: Book Three, Chapter 25
John of the Cross, St. 1991, The Collected Works of St. John of the Cross, Revised Edition, translated from the Spanish by Kavanaugh, K and Rodriguez, O with revisions and introductions by Kavanaugh, K, ICS Publications, Washington DC.