Even if you're improvising, the fact that beforehand you know certain things will work helps you make those improvisations successful. It really helps to have a certain amount of knowledge about musical structure.
“What you do as a policeman might be the right thing to do, but it's not entertaining. I left that behind me.”
“For me, acting was a way of taking destructive energy and doing something productive with it, and in that way it was quite a life saver.”