Strengths include things like the ability to find humor or summon enthusiasm, appreciation of beauty, curiosity and love of learning. The idea of the exercise is that using one's major "signature" strengths may be a good way to get engaged in satisfying activities.

These two exercises were among five tested on more than 500 people who'd visited a Web site called "Authentic Happiness." Seligman and colleagues reported last year that the two exercises increased happiness and reduced depressive symptoms for the six months that researchers tracked the participants. The effect was greater for people who kept doing the exercises frequently. A followup study has recently begun.

Another approach under study now is having people work on savoring the pleasing things in their lives like a warm shower or a good breakfast, Parks said. Yet another promising approach is having people write down what they want to be remembered for, to help them bring their daily activities in line with what's really important to them, she said.

Lyubomirsky, meanwhile, is testing some other simple strategies. "This is not rocket science," she said.

For example, in one experiment, participants were asked to regularly practice random acts of kindness, things like holding a door open for a stranger or doing a roommate's dishes, for 10 weeks. The idea was to improve a person's self-image and promote good interactions with other people.

Participants who performed a variety of acts, rather than repeating the same ones, showed an increase in happiness even a month after the experiment was concluded. Those who kept on doing the acts on their own did better than those who didn't.

Other approaches she has found some preliminary promise for include thinking about the happiest day in your life over and over again, without analyzing it, and writing about how you'll be 10 years from now, assuming everything goes just right.

Some strategies appear to work better for some people than others, so it's important to get the right fit, she said.

But it'll take more work to see just how long the happiness boost from all these interventions actually lasts, with studies tracking people for many months or years, Lyubomirsky said.

Any long-term effect will probably depend on people continuing to work at it, just as folks who move to southern California can lose their appreciation of the ocean and weather unless they pursue activities that highlight those natural benefits, she said.

In fact, Diener says, happiness probably is really about work and striving.

"Happiness is the process, not the place," he said via e-mail. "So many of us think that when we get everything just right, and obtain certain goals and circumstances, everything will be in place and we will be happy.... But once we get everything in place, we still need new goals and activities. The Princess could not just stop when she got the Prince."

On the Net:

Seligman Web site: www.authentichappiness.sas.upenn.edu/