Don't Worry, Be Happy. Bobby McFerrin's exuberant song seemed so simple: Happiness will fall upon you if you just stop fretting.

But when Republican presidential candidate George Bush Sr. adopted Don't Worry, Be Happy as his cheerful campaign song, all of a sudden McFerrin was not happy. He was angry.

Truly, happiness is not easy to maintain. Given that the subject of happiness covers almost everything that matters about human existence, it's understandable: Happiness is complicated.

Here are five useful things I've learned writing this series on the psychology, economics, philosophy and spirituality of being happy in difficult times: 1. Happiness can be measured.

Happiness wasn't taken too seriously for most of the past 100 years. Instead, influential thinkers tended to focus on all the things wrong with humans. Two horrendous world wars can do that.

But, in the past decade or so, research psychologists made it clear they could measure people's moods. Neurobiologists could also pinpoint brain patterns associated with wellbeing. And statisticians could collate thoughts about what humans find satisfying.

As a result, happiness has become a subject of scientific research, which is today's quickest route to social acceptability.

That's helped economists, the most politically powerful of academics, to finally take an interest in happiness.

After putting most of their energies into measuring only market activity, some economists have been realizing there are many other ways to chart a society's wellbeing.

It's sparking what could turn into a revolution in social and economic policy.

Read more here:

Don't worry, we can all be happy