18 (Aids to encourage the spiritual life.) In order that, in all conditions of life, they may be able to grow in union with Christ, priests, besides the exercise of their conscious ministry, enjoy the common and particular means, old and new, which the Spirit never ceases to arouse in the People of God and which the Church commends, and sometimes commands, for the sanctification of her members. Outstanding among all these spiritual aids are those acts by which the faithful are nourished in the Word of God at the double table of the Sacred Scripture and the Eucharist. The importance of frequent use of these for the sanctification of priests is obvious to all. The ministers of sacramental grace are intimately united to Christ our Savior and Pastor through the fruitful reception of the sacraments, especially sacramental Penance, in which, prepared by the daily examination of conscience, the necessary conversion of heart and love for the Father of Mercy is greatly deepened. Nourished by spiritual reading, under the light of faith, they can more diligently seek signs of God's will and impulses of his grace in the various events of life, and so from day to day become more docile to the mission they have assumed in the Holy Spirit. They will always find a wonderful example of such docility in the Blessed Virgin Mary, who was led by the Holy Spirit to dedicate herself totally to the mystery of man's redemption. Let priests love and venerate with filial devotion and veneration this mother of the Eternal Highpriest, Queen of Apostles and Protector of their own ministry. In the fulfillment of their ministry with fidelity to the daily colloquy with Christ, a visit to and veneration of the Most Holy Eucharist, spiritual retreats and spiritual direction are of great worth. In many ways, but especially through mental prayer and the vocal prayers which they freely choose, priests seek and fervently pray that God will grant them the spirit of true adoration whereby they themselves, along with the people committed to them, may intimately unite themselves with Christ the Mediator of the New Testament, and so as adopted children of God may be able to call out "Abba, Father" (Rom 8:15).
Source: Presbyterorum Ordinis (Vatican.va)