This has been a lifelong struggle for me. When I was younger, I would tell people that I wasn't negative, I was just a realist. I know for sure that I'm afraid to think positively because I'm afraid I'll not be prepared for a negative event. My mind wants to explore all possibilities so that I will be prepared. I also am afraid to say something positive out loud. I'm one of those people who will "knock on wood," after I make a positive statement. I'm afraid that if I say something positively, I will be jinxed and something bad will happen.
In the past 10 years, I've been working on this. I try to think more positively. I'm still afraid to say positive things out loud.