The Totus Tuus of St. Loius de Monfort's from his "Treatise on True Devotion to the Blessed Virgin."
Totus tuus ego sum, et omnia mea tua sunt. Accipio te in mea omnia. Praebe mihi cor tuum, Maria.
I belong entirely to you, and all that I have is yours. I take you for my all. O Mary, give me your heart.