I've always wanted some cause, something great to give myself wholly to. Is that a symptom of simply not wanting to think for myself? Is it a vestigial need for God? (Whom I have found) Is it a search for the right occupation or woman or what?
It is, in my opinion, just a basic human need. We have to identify ourselves some way. I went through the same thing for some time. I tried to be a musician... just not motivated enough. Tried to be a good boyfriend/husband... well, I just don't have a way with women, so that hasn't panned out. I looked for a career for awhile and nothing seemed to show itself. I used to be a very active Christian, but now I'm an atheist/agnostic, depending on how my tea sits in my belly. I've always enjoyed reading, but never found a subject I was interested enough to become an expert in.
Then I found the Air Force. I am waiting to be shipped in July. Life is good. I don't care about girls anymore. (Well, I'm still a guy, but I don't fret over them.) Everything else in my life is secondary now, and because of that, so much better. I have a future, I have a plan, I have a purpose, and I have approval. (From those that it matters to me, at least.) I'm doing a good thing, too... something people call unselfish, yet it's something that I want to do.
You just have to find what's right for you, what fulfills you. When you find it, don't ask why, just grab onto it.