You know exercise is good for you, but … (insert personalized excuse). If motivation is your problem, here's a nudge: new research shows exercise can also add to your happiness while slimming your waistline.

A new Gallup Poll shows Americans who exercise at least two days a week for 30 minutes a day report more happiness and less stress than those who don't and the benefits reportedly increase up to six days a week. The "happiness" index decreases slightly for those who exercise every day without a day off.

Even so, 49 percent of Americans exercise less than three days a week, according to the poll released last week. And while there are no known studies of how frequently Utahns exercise or how it affects their happiness, an exercise specialist at the University of Utah said residents of the Beehive State have one of the lowest obesity rates in the country.

Traci Thompson is director of the PEAK Academy, a clinic of the exercise and sports science department at the U. She can't give specifics about how Utahns in general view exercise or what kind of priority they give to it, but there are environmental factors at work in how residents make those decisions.

In 2007, 21.8 percent of Utahns were obese, she said, noting only three states had a lower rate. In general, residents live in "relatively safe neighborhoods," which encourages outdoor activity, she said.

She said the U.S. surgeon general also considers gardening and yard work as physical activity. "I would be willing to guess that because Utah is less urban and more suburban, that many are getting out to do the minimum like shoveling snow and mowing their lawn, where in other places they wouldn't need to do that."

Thompson said as health-care costs continue to rise, more companies are being forced to look at prevention, including wellness programs and incentives for getting employees to exercise to keep their insurance premiums down.

Even so, Utahns are busy and many say they just don't have an extra 30 minutes a day. But Thompson tells her clients they're setting an example for their children, and that can have lifelong health impacts, good or bad, she said.

The poll results came from 400,000 interviews conducted during the past year, and found that only 27 percent of Americans exercise five or more days a week.

Thompson's recommendations for those who need motivation:

 Walk to/from school and before or after dinner. "It doesn't have to be all at once."

 Use a pedometer. Start a family competition; compare distance regularly.