Ballet, followed by ballet and then a lot of ballet.
Ballet teaches you so much more than steps. It teaches discipline, reliability, body awareness and posture.
I coach adult swimming (!) and I am always giving them ballet pointers. They don't know its ballet, but it is.
Dance is how I got through phys. ed. in college. I wasn't even any good at all, but I learned so much.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher