The Cynical Life

I am usually trying to decide what is more important, Doing what you want, or doing what you need. Usually when you do what you need to or should do, you are left with the afterthought that you should have done what you wanted. This seems to lead to unhappiness, but you did what you needed to. And in the same breath is what you want, really what you should do? And how do we know what we need. We always know what we want but how do we know what is best for us in the long run. In short.. Im confused at life right now.