your Predominant fault
Your predominate defect is an interior failing that tends to prevail over all your other defects. It tends to affect your feelings, judgments, and nearly everything else, and it often leads to many other sins and defects. Father Garrigou-Lagrange calls it "our domestic enemy" and says it is "dwelling in our interior; for, if it develops, it may succeed in completely ruining the work of grace in our interior life." Whether you realize it or not, you are involved in spiritual warfare. You must identify and conquer your predominate spiritual defect in order to resist the devil’s temptations and his significant power over you.
Because of the fall we do not have access to our soul. Self-love deceives us and keeps us from being a good judge of our own defects. Identification of our predominant defect is as much a spiritual exercise as it is anything else. Pray to your Guardian Angel, Our Lady of Sorrows, and the Holy Spirit for enlightenment.
Self-knowledge is essential to advancement in the spiritual life. It is no surprise that the other pillars: spiritual reading and mental prayer, are crucial in this regard. In addition we need to examine our external behaviors for signs of what our defect may be. We must also examine where we are tempted. Satan knows your predominate defect and will attack there.
Eradication of your predominate defect occurs through several actions: (1) Strengthening the interior life, particularly with the aid of mental prayer and spiritual reading (2) pray for the graces to overcome the defect, use of binding prayers (3) strive for the virtue that is opposite the defect and develop a virtuous habit (4) regular and sincere examination of conscience (5) embracing penance and suffering