You must have some vision for your life. Even if you don't know the plan, you have to have a direction in which you choose to go... You want to be in the driver's seat of your own life because if you are not, life will drive you.
I approach every part I'm asked to do and decide to do from exactly the same angle: who is this person, what does he want, how does he attempt to get it, and what happens to him when he doesn't get it, or if he does?