Not an essay this time, just a quick sound byte. While reading the blog of Allen Hunt, who is converting to the Catholic Church, I saw a comment by someone (on a different subject) about being a believer, but not understanding why attending Church is necessary. The commenter mentioned enjoyment being a factor. I'm not going to say that one should not enjoy Sunday Mass, because one should, but the purpose of Mass is not enjoyment. Enjoyment flows from understanding the true purpose of Church.
God instructed humans from Adam and consistently to the teachings of Jesus Christ in the Gospels that humans are to perform sacrifice to him. God, who knows people better than they do themselves, knows that people need a regular reminder that God must take the first priority in people's lives, otherwise they forget what humanity is throughout their secular life also. Jesus Christ did not take away God's instructions to perform sacrifice. He changed the form in two fundamental ways. One is that Jesus emphasized the need for frequent prayer. While Jesus did pray alone he mostly prayed with the communion of his Apostles, disciples and family. Remember, he taught people how to pray. So the Mass is the structure for the communion of prayer where the faithful gather together and pray to God. Second the Mass is the place of the sacrifice to God. Jesus changed the sacrifice from one of animals, grain, and treasure to the temple (the Old Covenant) to the New Covenant, which is the commemoration and celebration of the bloodless sacrifice through the offering up of Jesus Christ in Holy Eucharist. So it is essential that the faithful continue to gather together to sacrifice (their time, attention and devotion) to God by attending Church.
While I don't like to use analogy to discuss the Mass, I understand that society has changed so fundamentally that there is not a solid foundation of comprehension of the humanity-God connection that there used to be until recent times. People in recent decades have gone from having a historical and instinctive understanding of their relationship to God to a time of "self help books" and "consumerist spirituality" that I understand that some sort of pop psychology analogy would be useful.
In Mass you are introduced to God in God's "authentic" form. For example, one of the hymns is a quotation of angels who praise God as actually seen and recorded in the Bible. Pop psychology urges people to get to know their "authentic" selves. Well, in the Mass you learn who God "authentically" is as God himself articulates and emphasizes.
Second, we know that children thrive in structure and fall apart where there is no structure. The performance of sacrifice was devised by God and instructed to humans so that like children with schedules and understanding of what mature behavior entails, adults remember and renew their understanding of the structure of their relationship with God when they participate in Mass. As a simple corrolary to this example, what children learn in school, sports, or music lessons if they never have practice and homework? So Mass provides not only necessary structure for one's mature relationship with the Lord, it is also the weekly homework of the schooling. The Mass is repeated through the liturgy, providing the structure and reinforcement, while the Bible readings change and provide the continual learning, like homework and practice.
Third, while individual prayer is very important, the sacraments are vehicles for obtaining more grace. I would be hesitant if I were you, dear reader, to assume that you have "enough" grace at any point in your life. Even the Apostles, including St. Paul himself, never assumed that.
I hope this helps. If people really understood the necessity for the Mass they would be knocking each other over in the stampede to get to Mass every week.