There's a beautiful song illustrating this truth, "Breath of Heaven" by Amy Grant. I heard it for the first time a couple weeks ago, and it has quickly become one of my favorites.
I have traveled many moonless nights
Cold and weary with a babe inside
And I wonder what I've done
Holy Father, You have come
And chosen me now, to carry Your Son
I am waiting in a silent prayer
I am frightened by the load I bear
In a world as cold as stone
Must I walk this path alone?
Be with me now, be with me now
Breath of Heaven, hold me together
Be forever near me, Breath of Heaven
Breath of Heaven, lighten my darkness
Pour over me Your holiness, for You are holy
Breath of Heaven
Do you wonder as you watch my face
If a wiser one should have had my place
But I offer all I am
For the mercy of Your plan
Help me be strong, help me be, help me
"The angel Gabriel said, 'Hail, full of grace, the Lord is with you.' But she was greatly troubled at what was said and pondered what sort of greeting this might be. Then the angel said, 'Do not be afraid, Mary, for you have found favor with God."
~Luke 1:28-30