In one of the early Lives of Francis of Assisi we read:
The saint, therefore, made it a point to keep himself in joy of heart and to preserve the unction of the Spirit and the “oil of gladness” [Ps 45:7]. He avoided with the greatest care the miserable illness of dejection, so that if he felt it creeping over his mind even a little, he would have recourse very quickly to prayer. For he would say: “If the servant of God, as may happen, is disturbed in any way, he should rise immediately to pray and he should remain in the presence of the heavenly Father until he “restores unto him the joy of salvation.” [Ps 51:12]
Francis, too, seeks to respond quickly and decisively to the first, small beginnings of disquiet: “if he felt it creeping over his mind even a little, he would have recourse very quickly to prayer.” This immediate, prayerful, and resolute response to an enemy who is “weak when faced with strength,” renders a snowball effect highly unlikely. In this response, Francis practices precisely what Ignatius teaches in the twelfth rule, a teaching that enables us to shatter much of the enemy’s ability to hold us in bondage. Through it, like Francis, we abide “in joy of heart” and preserve within us “the unction of the Spirit and the oil of gladness.”
Gallagher, Timothy M. . The Discernment of Spirits (pp. 223-224). The Crossroad Publishing Company. Kindle Edition.
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