Here are the words of my Bishop, Bishop Timothy McDonnell, on the start of Advent. They were written in "The Catholic Mirror," the magazine of the Diocese of Springfield, MA.
On each of the four Sundays of Advent, as an additional candle is lit, you might want to reflect on a particular aspect of God's presence in your life.
C: Christ came to us the first Christmas.
O: Christ comes to dwell in others and ourselves.
M: Christ is present to us at Mass and in the sacraments.
E: Christ will come again at the end of time.
In other words, Advent is not simply a season in which we get ready to celebrate Christmas. It is not merely a time in which we consider the way God set the stage for the birth of Christ. Advent is more. It is a time to pray, "Come, Lord Jesus. Come to us as once You came at Bethlehem. Come and help us see your presence in us and in others. Come and deepen our recognition of you at Mass and in the sacraments. Come to make all things new."