NEW YORK (Reuters Health) – The factors that motivate people to start exercising are not necessarily the same ones that will drive them to stay active over time, a new study suggests.

While many sedentary people move past the initial hurdle of getting off the couch and into their running shoes, research shows that the real challenge is sticking with a commitment to exercise.

Experts recommend that healthy adults get at least 30 minutes of moderate exercise, such as brisk walking, on most days of the week. Yet studies indicate that only about one-third of U.S. adults are regularly active.

In the new study, published in the Annals of Behavioral Medicine, researchers looked at the factors that typically motivate people to begin, and then maintain, an exercise regimen.

They found that among 205 initially sedentary adults, certain factors separated those who began working out within the next six months and those who remained couch-bound. For example, people who bought home exercise equipment were 73 percent more likely to start exercising than those who eschewed such gear.

The bad news was that home equipment did not seem to keep people active over the long haul; it was not linked to better odds of being active at the one-year mark, the study found.

On the other hand, people who generally had a stronger sense of self-efficacy — a belief in one’s ability to accomplish goals — were more likely to be exercising at any point, but this trait was more important in keeping people active than in getting them to start in the first place.

Similarly, people who viewed exercise as satisfying or rewarding were more likely to stay active over one year, but that belief did not seem to drive people to start exercising.

The findings do not prove any cause-and-effect relationships, according to the researchers, led by Dr. David M. Williams, of Brown University and The Miriam Hospital, Centers for Behavioral and Preventive Medicine, Providence, Rhode Island.

That is, buying exercise equipment is no guarantee that a person will actually start using it, and being self-assured does not necessarily mean that someone will become a lifelong exerciser.

But whatever inspires people to become active, they should realize that the toughest part is keeping it up, according to Williams.

The situation, he told Reuters Health, is similar to other long-term challenges, like losing weight or quitting smoking.

“There are likely to be different factors that help you maintain your exercise program than the factors that helped you get started to begin with,” Williams said.

“Just like with weight loss and addictions, exercise must be thought of as a lifestyle change, with constant attention to maintaining the program,” he noted. “Otherwise, yo-yo exercising is likely.”

SOURCE: Annals of Behavioral Medicine 2008.