The Greatness of Complete Mastery

You know what I really want? To develop complete mastery, total proficiency, expert, and adept command of something valuable, something awesome and useful. I've touched that level of skill and understanding with a few useless things like games, but I would really like to develop those abilities in something more widely-applicable and more worthwhile in life. I just have to find something that I have enough passion for, to invest the time and effort.