Humility might be defined as taking one's true measure" and then not hiding from the truth of that realization. Humility, is a state that is achieved, not through practice, but through awareness.
Benjamin Franklin, at one point in his life, made it a practice to work on one virtue each week. He was making excellent progress, he felt, in his self-development until he worked on humility. What he found was that, as often as he practiced, and made himself more conscious of humility in his life, the prouder he became of his own progress.
What then is your true measure? In the context of this world, you are one among billions, here for but a single breath. You matter to very few people, and even the few who know you may think about you seldom.
Without humility, we can be as puffed up about ourselves as the gnat in the following story: A self-important gnat, having raised his family for some years in the ear of an elephant, finally decided to move. Shouting at the top of his lungs, he informed the elephant of what was, to him, a momentous decision. The elephant, having previously known nothing of the gnat's existence, made no reply, not wishing to hurt the feelings of his small and totally insignificant visitor.
Even if you see yourself as a part of all creation and lasting for eternity, you, as a single human, are still but a drop in a vast ocean. That ocean is held by gravity to a small sphere orbitting a tiny star among billions of others. Your time as a separate drop, however important you may seem to be in your own world, is so brief that the ocean itself may be unaware of your existence, your forming, or your dissolving.
"All my brothers are better than I!"
"How is that?"
"Every one of them considers me more worthy than himself, and whoever rates me higher than himself is in fact better
than I." - al Ghazzali
Excerpt from Essential Sufism by James Fadiman & Robert Frager