"There is no such thing as maturity. There is instead an ever-evolving process of maturing. Because when there is a maturity, there is a conclusion and a cessation. That’s the end. That’s when the coffin is closed. You might be deteriorating physically in the long process of aging, but your personal process of daily discovery is ongoing. You continue to learn more and more about yourself every day." — Bruce Lee

Some of the smartest and most successful people I know are "big kids" in their 40s, 50s, and 60s. They never "grew up" but they never, ever stopped exploring, discovering, learning, and growing. They are fun and inspiring to be around. They take self-education and their missions and their work very seriously, but they do not take themselves seriously at all. Life is too important (and short) to take yourself seriously.