Humility is a not a weakness nor is it shyness.  In fact, humility is a strength that we often overlook.  Excellence in anything, whether sports, business or leadership is sourced in the realization and self-awareness that growth and learning is still possible and necessary even when expertise is obtained.  Those without humility turn off the learning process once they achieve a little success or expertise.  But the true masters teach themselves to maintain the attitude of a beginner, one who is constantly learning and experimenting with new ideas and techniques and it is this attitude that truly marks as master as being one.  If you want to find a true master, look for humility as the marker.  Those who are arrogant may have skills but haven't yet mastered their craft but those who are humble and are committed to continuous learning are where the masters reside.

Pride makes us artificial and humility makes us real. Thomas Merton

Real genius is nothing else but the supernatural virtue of humility in the domain of thought. Simone Weil

A great man is always willing to be little. Ralph Waldo Emerson