Coca-Cola would like consumers to believe that happiness can be bottled up in just 12 fluid ounces (355 milliliters) of sugary goodness. The company's soda ads pair its products with the most enjoyable times in life -- neighborhood cookouts, movie dates and hanging out with near and dear ones. In Africa, this Coke-happiness correlation may have more behind it than just marketing dollars. In times of war and political strife in recent years, Coke sales have dipped; when stability returned, so did the soda consumption [source: Economist].
Monitoring someone's Coke consumption isn't the most scientific way to gauge happiness. But the Africa anecdote is an example of the relationship between emotional states and behavior. It's well understood that our feelings often affect actions. Confidence, for instance, breeds socialization, and apathy fosters withdrawal.
Interpreting the emotions behind the exhibitions isn't always simple. When asked, most people will concede that they're happy [source: Soltis]. They may not be over the moon in rapture, but they're far more likely to describe themselves as at least slightly happy than as unhappy. At the same time, the National Institutes of Health report that about 6.7 percent of adults in the United States deal with major depressive disorder.
While you can't equate depression with run-of-the-mill unhappiness, there does seem to be a disconnection between reported and actual happiness. In that case, certain behaviors signal that negative emotions are taking a toll. After recognizing them and taking action, folks can get back on track toward joy.