As a student, FIRST gave me my life back--or perhaps more accurately, it made me want to take my life back. After my father was killed, I spent several years losing the battle with PTSD until robotics helped remind me what life was worth. It ignited my obses--passion, helped me realize me dream, let me mature almost exponentially, and introduced me to some truly amazing people who helped fill the hole in my family life. I couldn't have asked for more; I couldn't even have thought to.
As a mentor on the other hand, it's made me insane. Well, perhaps that actually started when I was a student.
All that's on top of the ridiculously cool (not to mention useful) engineering, teamwork, leadership, and life skills I've gained and the overall fun of FIRST, of course.