Partly, some health experts argue (and this is the one surprising finding), it's because we're too optimistic. Blame it on something called the optimism bias, a natural human inclination to see everything—our situation, our future, our prospects—through rose-colored glasses. That bias lets people deny that our stressed-out lives are bad for our health—harm that far outweighs the measure of relief optimism can bring.

Optimists believe they have more control over their lives than they do. And though the bias toward optimism helps us cope to some degree, it often can deceive us into ignoring a danger, experts say.

People who constantly play the "everything is great" game might be less worried about things they should be very worried about—think health scares. They're also the type who expect a bad situation will either go away or work itself out—even something as dangerous as domestic violence. Obviously these are not times for optimism. Plus, when things go woefully wrong for optimists, chances are they'll become incredibly stressed out.

Taking in all this information is stressful in itself—but it can easily be explained in consumer-speak: Just like everything else, too much of something isn't good (including optimism). Stress is no good, but neither is denying its existence. So maybe my  way of looking at things is wise after all because when your glass is half empty, it's easier to stay calm—and kinda happy.

Just not too happy.