One of the things people notice about the respective starts of all four New Testament Gospel writings is the way that from the very beginning they lay out foundational truths about God and his work in our lives.  We confess as Lutherans* that in original sin our will is turned against God, but that God through his mercy turns our will to him.  A key verse is from Jesus’ teaching the night before he dies where, just after saying ‘I am the vine and you are the branches’ (John 15:5), he says ‘You did not choose me, but I chose you and appointed you to go and bear fruit – fruit that will last!’  (John 15:16). And so it is that God chose Mary and appointed her to bear his Son Jesus Christ who would die for the sins of the world on the cross of Calvary and truly yield fruit that will last.  God has always been at work choosing his people and turning their will toward him to receive his grace.  Now some 2020 years later we continue stepping into God’s ancient and great plan of salvation as we join with Mary in proclaiming ‘I am the Lord’s servant… may it be to me as you [God] has said… My soul glorifies the Lord… he has performed mighty deeds with his hands’ (Luke 1:38;46b, 51)
*See Article II, Free Will in the Formula of Concord (Pastor Matt can provide this to you on request).