What keeps me from "rejoicing in the Lord always" as the Entrance Antiphon tells us we should do? Is it mostly things outside of me that take away my joy or things inside of me? Are these things under my control? Does God have power over them?
The Entrance Antiphon tells us we should always rejoice because "the Lord is near." If the Lord is with us, nothing can really harm us. No matter how sick or sad or set upon we feel, if Jesus is with us and within us we have everything we need for the fullness of joy - forever.
Jesus is God. God is everything that is good, everything desirable. If we are united to Jesus and God through grace, we have within us right now everything we will need or desire for all eternity. Anything we are suffering right now is like the pain of standing in the cold for a few minutes waiting for the door to open to a party.
The Opening Prayer invites us to "look forward to the birthday of Christ" during Advent, and the Alternative Opening Prayer invites us to take another step and "look forward with longing to his return at the end of time." This puts our focus on the "wedding banquet of the Lamb," when we will celebrate his birth and ours, his life and ours, his nuptials and ours for all eternity in the party to beat all parties. Before Communion at Mass, in a defiant response to every suffering, every persecution, and to death itself, the Church places us in the "end time." The "marriage of the Lamb has come, and his bride has made herself ready." The Church is "coming down out of heaven from God, prepared as a bride adorned for her husband." Then the presiding priest proclaims in the words of the angel, "Blessed are those who are invited to the marriage supper of the Lamb." Anyone who kills us is simply opening the door for us to the "wedding banquet of the Lamb." This is reason to "Rejoice in the Lord always."
Advent is dedicated to looking forward. This third Sunday of Advent is called "Rejoice (Gaudete) Sunday" to remind us that "the Lord is near."