Over the weekend I watched Night at the Museum 2 with my nephew. In it, Robin Williams’ Teddy Roosevelt character says that the secret to happiness is diet and exercise. I was delighted by that line — so true…and yet so difficult. Why is that? We all know that a good diet and regular exercise have a slew of mental and physical benefits alike, but for some of us, that knowledge simply isn’t enough to motivate us into action.

While this is true for the general population, it may be even more true for patients with rheumatoid arthritis, or RA, an autoimmune disease in which the body attacks its own joint tissue. Just as for the rest of us, research shows that maintaining a regular physical activity plan can help control an RA patient’s symptoms. But those symptoms include things like joint damage, pain, disability, and increased cardiovascular risk — all things that would certainly scare me away from exercising.

At this year’s annual conference of the American Physical Therapy Association, Northeastern’s physical therapy department chair Maura Iversen, along with several of her students, presented new work about the relationship between RA and physical activity. They presented results from two research NIH funded research projects that explored how physical activity and disease activity correlate and what factors distinguish very active and very inactive patients.

The first study was a statistical analysis of 892 patients over age 18. Iversen’s team found, as they expected to, a “small but significant” correlation between disease and physical activity — meaning that patients with more active symptoms were less likely to exercise. The research team makes no claims about why this is, but I’m willing to go out on a limb and say that as those symptoms get worse, exercise becomes less and less appealing. Even if you you do know that exercising would help tamp down your disease activity.

They also found a few factors that correlated with increased physical activity: Women, people with stronger social networks, teetotalers, and the more well-educated among the group tended to be more active.

The second study was a more objective look at how RA patients engage with physical activity. They selected a group of patients based on their answers to a physical activity survey — the most and least active 10 percent. Then, they got them all together in small focus groups and led discussions about physical exercise and rheumatoid arthritis. They recorded and analyzed the discussion conversations and found five emergent themes, which seem to me to be in line with the results from the first study:

Social support was important both in helping highly active people stay active and in getting inactive people to start exercising. Environmental factors and ease of access were also important, “it’s easier to start and keep motivated if the classes are easy to get to,” said one participant.

Highly active participants differed from their less active counterparts in the way they viewed the impact of physical activity on their disease state. “We found that patients with RA who remain active conceptualize activity as a drug,” said Iversen. “The sedentary group saw it as a nice thing, but not a medication to help treat their disease.”

It was easier for patients who were active before their diagnosis to remain active than it was for historically inactive patients to start up a new routine…which doesn’t surprise me a bit. I know how hard it is to start and maintain an exercise routine, not being naturally inclined to move as some of my uber-fit friends.

Finally, and this is perhaps one of the most interesting findings, patients in both groups associated physical activity with independence. The difference is that less active patients regret their loss of physical independence whereas highly active patients claim their independence through exercise.

That last bit brings me back to Robin Williams’ fictional Teddy Roosevelt. While I’m not about to launch into a philosophical rumination on the relationship between happiness and independence, I would like to point out how so much of this has to do with one’s state of mind and how it affects the way we approach difficult tasks that we know will improve both our mental and physical health.

One comment by a less active patient said that two of his/her kids call every single day to find out where their parent is planning to walk that day. That’s an example of the social network having an impact on one’s physical activity. Teddy Roosevelt’s secret to happiness statement is in response to Ben Stiller’s night guard character, Larry Daley, who says he thinks the secret is doing what you love and being around the people you love. Turns out being around the people we love may just improve our exercise habits, at least this study suggests so in the case of rheumatoid patients. And I would venture to guess we’re not all so different.