I'm in the same boat. I am a negative thinker, just from experience with things not working out as i would have liked. The thing to remember although is that when one door closes another opens. There were reasons why things didn't work out for me as hoped as other opportunities turned up around me. I am still a negative thinker still and am reading a book called Perfectly Yourself by Matthew Kelly that has some good points about thinking positive and doing your own thing. I havn't finished it yet but am planning on it soon.