Oh, who can explain the extent of the denial our Lord wishes of us! This negation must be similar to a temporal, natural, and spiritual death in all things; that is, with regard to the esteem the will has for them. It is in the will that all negation takes place. Our Savior referred to this when he declared: Whoever wishes to save his life will lose it (Those who want to possess something, or seek it for self, will lose it); and whoever loses his soul for my sake will gain it (Mt. 16:25; Lk. 9:24). This latter means: Those who renounce for Christ all that their wills can both desire and enjoy by choosing what bears closer resemblance to the cross — which in St. John our Lord terms hating one’s own soul (Jn. 12:25) — these same will gain it.
Saint John of the Cross
The Ascent of Mount Carmel II, ch. 7, no. 6
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.