What Do You Do Outside of the Office?

What do you do to stay mentally and or physically fit? Well, for mental fitness, obviously doing research and being challenged by my students. I'm not a very good squash player, but what I lack in skill I make up for in enthusiasm. My kids are still my number one focus; spending time with them has been my best source of relaxation. What is it that you know about financial engineering today that you wish you knew 30 years ago when you were first arriving at MIT? I wish I understood just how important human emotion is in financial decisions.