Caring for an Alzheimer's patient is a situation that can utterly consume the lives and well-being of the people giving care, just as the disorder consumes its victims.
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.
Why should I say I will retire in three or four years? You retire the very moment you utter those words.