Bad moods?

Where do bad moods come from, anyway? Do we subconsciously or consciously choose to be unhappy when things don't happen the way we wanted? Can you really just "wake up on the wrong side of the bed"? Can bad moods be prevented? Why are some people in bad moods/more moody than others? Is it personality or circumstance? 

Well I want to know. 

I think you can wake up in a gross mood. And your expectations gotta have alot to do with moods. Like when you expect to have a good time, you usually do. And when you let your happiness rest on shifty things like the weather, you're usually more moody. 

And when you expect the weather to be rainy, its not as bad as expecting it to be sunny and then having it rain. I do think that you can choose to be happy instead of in a bad mood, but sometimes it's comforting to be in a bad mood. I guess it feels good to feel sorry for yourself sometimes. There have to be alot of factors that come into play. I don't think it's just one thing, and that's why its so hard to get rid of bad moods. And you can't really be in a good mood all the time, can you? Besides, it wouldn't be anything special then. 

What about diet? and sleep patterns? If your body feels good because you take care of yourself, then you'll probly be in a good mood more often..

I want to be in a good mood more often. But I eat fairly healthy. And I get 9hrs of sleep a night. And I find that I drift into the best moods when I'm at peace with my good friends, when I'm doing my best in school, and when it's extremely warm and sunny outside. I'll probly end up moving to FL after college.