Everyone has their own way of looking at things. I'm well aware that the glass can be drained at any time, but I've always been a "the glass is half full" kind of guy.
If things don't turn out the way I'd prefer? At least I didn't spend most of the time worrying and complaining. If things do turn out the way I'd prefer? At least I didn't waste all of my time worrying and complaining (in this case for nothing).
For me it makes for a more pleasant life all around :)
Coyote