Wise words from Seth Godin:
The first is that it doesn't work. You can whine about the government or your friends or your job or your family, but nothing will happen except that you'll waste time.
Worse... far worse... is that whining is a reverse placebo. When you get good at whining, you start noticing evidence that makes your whining more true. So you amplify that and immerse yourself in it, thus creating more evidence, more stuff worth complaining about.
If you spent the same time prattling on about how optimistic you are, you'd have to work hard to make that true...