Praised be Jesus and Mary, now and forever.
The Church celebrates the Nativity of Our Blessed Lady, but since the Church celebrates only the feasts of those who are already saints, it follows that already at her birth, Our Lady was a saint, a great saint, and that shouldn't surprise us because we know even more, already at her conception Our Lady was a saint, and a great saint. In fact, Our Lady's birth was not even her starting point, her Immaculate Conception was, and by the time of her birth, she had already been growing in holiness for nine whole months. So to try to understand Our Lady's holiness at her birth, let's rewind a little bit and try to think of just the starting point. 
What was Our Lady's starting point? Our Lady's initial grace, her holiness at her Immaculate Conception, was such that it was already greater than the final grace of all saints and angels put together. This is particularly the Franciscan position, Our Lady's starting grace, Our Lady's Immaculate Conception, the first moment of her existence was a holiness that was greater than the holiness of all the saints and all the angels of all time put together at the height of their holiness. So take Saint Michael, the archangel, take Saint Gabriel, Saint Raphael, add all the other saints, add all the other angels, all the doctors, all the fathers, Saint John Paul II, Mother Teresa, Padre Pio, Maximilian Kolbe, John of the Cross, Francis de Sales, all of them, put them together, take them at the height of their sanctity, add all the saints that you don't even know, every single citizen in heaven, and that's still less than the starting point was for Our Lady. Already at her Immaculate Conception, she was greater than all the saints and angels put together. That's why Pius IX said, she had a fullness of holiness greater than which none is at all conceivable under God and which no one, with the exception of God, can even grasp. And by the time of her birth, she had already been growing in grace exponentially, as Saint Alphonsus says, for nine months. Why? Because she had the use of reason as a special privilege already from her Immaculate Conception. For those nine months in the womb, Our Lady was knowing and loving God, practicing virtue, making acts of love for God.
The divine grace, as Saint Alphonsus, did not descend upon Mary in drops as upon the other saints, but as David predicted, like rain upon the fleece. The soul of Mary was like wool that happily imbibed all that great shower of graces without losing a single drop.
So the point here is Our Lady is truly full of grace, greater than any saint, all the saints, every saint from beginning to the end of time. 
She has a lot of grace and a lot of grace to share with us. God has made her our Mediatrix of grace. Our Lady wants to share this fullness with us, and she has done so. She has sanctified every saint that has ever lived, and she can do that with us. So the takeaway is, well, true devotion, consecration to Our Blessed Lady.
Saint Maximilian, already at the beginning of his life, when he was just ordained a priest, wrote this little prayer to Our Lady. Father Mary, I don't know exactly what you're going to do with my life, but I do know one thing, that you're going to make me a saint, and a big saint. That was in 1919, 22 years before he died. He didn't know exactly what Our Lady would do with him, but he was absolutely confident that she would make him a great saint, and she did that, and she has done that with every other saint. 
And Saint Louis de Montfort explains it well. When we consecrate ourselves to Our Lady, something special happens in exchange. The Blessed Virgin, Mother of gentleness and mercy, never allows herself to be surpassed in love and generosity. When she sees someone giving himself entirely to her, she gives herself completely to him. She engulfs him in the ocean of her graces, adorns him with her merits, supports him with her power, enlightens him with her light, and fills him with her love. All that fullness that Our Lady possesses that we just described, Our Lady shares that with those who consecrate themselves to her.
A true exchange occurs. A true exchange occurs, excuse me. She shares her virtues with him, her humility, faith, purity, etc. She makes up for his failings and becomes his representative with Jesus.
Just as one who is consecrated belongs entirely to Mary, so Mary belongs entirely to him. And we can truthfully say of this perfect servant and child of Mary, what Saint John in his gospel says of himself, he took her for his own. 
Just as one who is consecrated belongs entirely to Mary, so Mary belongs entirely to him. And this, this is something to which our Lord himself invites us. John, John's action, taking Our Lady into his home, taking Our Lady for his own, came in response to the invitation from our Lord from the cross, behold your Mother. Jesus says it to us, take her, take her as your mother. She's full of grace, full of grace for all the saints, and she's the maker of saints.
So let's respond also like the saints did, like Saint John did. We're taking Mary into our home, making her a part of our life, consecrating our whole life to her. 
Praised be Jesus and Mary, now and forever.