THURSDAY, Jan. 24 (HealthDay News) -- Performing small acts of kindness and gratitude can make people happier, researchers believe, but how this occurs is more of a puzzle.

Sonja Lyubomirsky, a professor of psychology at the University of California, Riverside, has studied happiness for more than 20 years. She and others know that positive activities boost positive emotions, thoughts and behavior, in turn improving well-being.

Now, how people can deliberately change their thinking and practices to bliss out to the max is her focus.

"I have evidence that the dosage of an activity is important," she said.

Reviewing past studies on happiness, including some of her own research, Lyubomirsky concluded there is no single prescription for happiness-boosting acts of kindness.

Variety, frequency and motivation all play a role, she said.

How often you perform the behaviors influences happiness, Lyubomirsky found, but not always in the way you may think. Studying the effect of counting your blessings on happiness, for instance, she found doing so once a week was ideal for making people happier.

"Doing it three times a week gave no extra benefit," she said.

Her research, presented at the recent annual meeting of the Society for Personality and Social Psychology in New Orleans, found that performing other positive acts once a week led to the most happiness. That could be because many routines, such as worshipping and even TV, occur weekly, she said.

Performing a variety of kind and grateful behaviors helps maximize happiness, too, whereas repeatedly doing the same act of kindness may lose its ability to boost happiness, she said.

"We did one study where we had people do acts of kindness over 10 weeks," she said. The acts could be similar or varied. For instance, someone who usually refused to take out the trash might offer to do so. That made them happier initially, she said, but it worked better in terms of happiness when they varied the activity.

Picking your own positive behavior, such as performing an act of kindness, promises to make you more likely to vary the activity, she also found.

Feeling you have social support for your actions also influences how much positive behaviors, such as expressing gratitude, will boost your happiness, she said. And gaining support through social media works as well as face-to-face "hurrahs," she added.

Commenting on the study, James Maddux, university professor emeritus of psychology at George Mason University, said he thinks "the message is, for these kinds of activities, it's not a matter of one-size-fits-all."

"You start with these general strategies," he said of behaviors such as performing kind acts. "X seems to work for most of the people most of the time."

The next focus, he agreed, is to tease out which differences in people affect the degree of happiness produced, as Lyubomirsky is doing.

Once people figure that out on an individual level, the research suggests they can expect their positive acts to repay them with even more happiness, he said.

Experts note that data and conclusions presented at meetings are typically considered preliminary until published in a peer-reviewed journal.

More information

For more about happiness, visit the Social Psychology Network.