Your mind is extremely powerful. If you go through life cynical and refusing to "trust" on your mind's potential
...being cynical has nothing to do with not "trusting" your minds potential. Theres a realistic point where "approaching or trying" for a goal stops being viable. Just as easily, I can say you waste more effort and time trying to achieve bluntly unrealistic goals(at a certain point), then what you do accomplish.
If thinking "positive" is just focusing on obtaining a goal, then I think theres nothing particularly special with "positive thinking," because that's simply being realistic. A lot of "positive thinkers" are unrealistic, fruity people who think life is sun shine and bubble gum. I would say there is a considerable difference between focusing on a goal you want to reach and trying to reach it, and thinking that outcome will happen regardless of reality.
Hahah have fun being depressed. I like being happy.
If happiness means being deluded then I'd pick un-happiness. I don't get the huge hard-on over being happy all the time either.