64. The brick walls are not there to keep us out. The brick walls are there to give us a chance to show how badly we want something. ------ Randy Pausch
"Stay foolish" is probably another way of expressing the Zen idea that you should keep "beginner's mind", the state of curiosity you have when you are a novice at something and learning. You're open to new things (because everything's new) and aren't afraid to make mistakes. The alternative would be the sort of attitude when things get routine, and you start doing things automatically, without really paying attention or giving it your full effort. Stay hungry just means to not become lazy and satisfied.