She recognized what direction her life must take, she understood, well enough at least, what the practice of virtue was going to mean for her. And she did it. She saw no need to constantly give herself marks, or ask anyone else to do so, on how well she was or wasn't doing. She saw no need to rate her own performance and virtue against that of anyone else. Not only did she have faith in God, she had, apparently, faith in herself, in her own ability to decide rightly, and once the decision was made, there was no need to rehash it over and over, to wonder if she had acted wisely, if she had had all the facts, and so on.
Advent closes, as it began, really, with an image of patient, trusting faith.
A faith that was composed of as much understanding as possible. Mary even questioned the angel for a few more details at the Annunciation., but a faith which did not depend on understanding for its force. Mary knew that her understanding would fall short of her vocation. It always does. If we choose no, then we are left to face life with pretty much only our own resources.