What Does Humility Have to Do with Martial Arts?

So in my time of training through Taekwondo, I have found that there is so much more to learn than how to throw a kick. While working on becoming an instructor, I have seen many of the "life-lessons," such as honesty, perseverance, and gratitude, take root in my training, both mentally and physically. Another big one, through becoming a leader in martial arts, is the importance of humility as both a martial artist, and a leader. My instructor wrote a thesis on the topic of humility link removed

I have found, can sometimes be the hardest skill to possess as a leader, but it could easily be one of the most important. Humility is not a bad thing, I don't think. It keeps our leaders in check, and it makes us humble, if accepted and learned from, and I think everyone needs to be humbled every now and again! To a student, seeing their instructor accept humility graciously, and learn from it; that is how they (the leader) will be more honoured by their students. What do you guys think? What have you learned about humility?