Self-will is the inclination to do our own will. On account of the corruption of human nature self-will is usually opposed to the will of God and is defined as such by spiritual writers. As heaven is the reward for doing God’s will, detachment is necessary for all. Children must renounce their will to obey their parents; citizens, to abide by the law of the land; and Christians, to become worthy brethren of Christ. Those, however, who seek perfection, must make the holy will of God their own in all things before they can say with Christ, “I do always the things that please him” (John viii.29). In fact, in proportion as we do God’s will we work for heaven, and in proportion as we do our own will we have our reward in its gratification. “Why have we fasted, and thou hast not regarded; why have we humbled our souls, and thou hast not taken notice? Behold, in the day of your fast your own will is found” (Is. iviii.3).
Peter Geiermann, The Narrow Way: A Brief, Clear, Systematical Exposition of the Spiritual Life for the Laity, and a Practical Guide Book to Christian Perfection for All of Good Will (New York: Benziger, 1914).
(H/T to Saintly Sages.)