How do You be More Positive?

I would really like to know this.

I think, whether your life is actually going fantastic or not, knowing how to be positive will make everything seem... better, I guess. Things may not be perfect and I'm not saying a change in attitude will fix everything, but I think it will help.

I have no idea how to be positive, though. I'm not wired in a way that allows me to highlight the good things and just skip over the bad stuff. I have to focus on the bad happenings in my life because I feel like if I go over them again and again, then maybe I can really learn from those experiences and they won't happen again. But that's not logical, is it? Bad things are going to happen in your life. That's just something that is unavoidable. (Apperantly I don't pay attention to that fact, though.)

When bad things happen to me, I almost shut down, depending on how severe I deem them. I'm always seeking out reassurance when the situation is really bad because I can't just listen to what I'm telling myself. It's like when these bad things happen, I feel like I'm inadequate in some way--that everything is entirely my fault and that I'm always the one who is at fault. (Again, though, that's not logical... is it?)

So, pretty please with a nice little strawberry on top, will you tell me how you stay positive? Any tips and tricks, links or advice is helpful.