“Holy Orders is the sacrament through which the mission entrusted by Christ to his apostles continues to be exercised in the Church until the end of time: thus it is the sacrament of apostolic ministry. It includes three degrees: episcopate (bishop), presbyterate (priest), and diaconate (deacon).” (Catechism of the Catholic Church, 1536).
Only baptized, Catholic men are called by the Church to become ordained and receive this sacrament. The man who is ordained a bishop or a priest receives a special grace to act “in persona Christi”, not based on his own power or merit, but in the person of Jesus Christ. Deacons “share in Christ’s mission and grace in a special way” (Catechism of the Catholic Church, 1570) to serve as Christ served.
A baptized, Catholic man can be validly ordained to that ministry. The sacrament is not merely something a man can just claim for himself, or discern alone. The sacrament is a unique calling that God gives to men that He has chosen to serve His bride, the Church. The decision to become a priest is not made in isolation - members of the community play an important role in supporting any individual wishing to discern God’s call to Holy Orders.
The purpose of a priest is to bring people to Jesus, and Jesus to people. He does this primarily by preaching the Word and offering the Sacrifice of the Mass. His daily life involves administering the sacraments and caring for the people in their daily needs.
You must pray every single day, asking God to reveal His plan for you. Do not ask yourself, “What do I want to do when I grow up?” This is the wrong question! Rather, you should be thinking and asking: “Jesus, what do You want me to do?” And listen for the answer! The primary locus of revelation is the heart. Listen with your heart! The discernment process in the priesthood must also include the Church. The local bishop is the one who ultimately decides who is and who is not called. He is assisted in this by the vocation office and the seminary. This whole process is called “discerning one’s vocation.”