Also, the transition into a life of specific purpose doesn't have to be an over night event. Taking small steps towards how you want to be could be the way.
Personally, I'm narrowing down what my purpose may be by constantly asking myself the question: Do I enjoy what i'm doing at the moment? (or, more straight forward: What is my purpose?)
Maybe it's just a matter of trying as many new activites as possible until you find what 'clicks' for you (depending on your current situation).