Mental Exercise

People who think they’re couch potatoes tend to have shorter lives.

By Diana Aguilera

Do you constantly judge how physically fit you are in comparison with your friends? If you feel like you’re lagging behind, you may want to change your mindset. It turns out your thoughts may be quite powerful.

Stanford University researchers recently found that people who think they are less active than their peers tend to live shorter lives, even if they get plenty of exercise.

“We’re underestimating the influence of our mindset, and it’s important that we take it more seriously in health and healing,” says senior author Alia Crum, an assistant professor of psychology at Stanford.

The study, published July 20 in the journal Health Psychology, analyzed the perceptions of more than 61,000 U.S. adults using data from three national health surveys. The researchers documented participants’ physical activity, health and personal background, and then zeroed in on one question: Would you say that, compared with others your age, you are physically more active, less active or equally active?

The researchers then viewed death records from 2011, some 21 years after the first survey was conducted. Controlling for such factors as physical activity, age, body mass index and chronic illness, they found that individuals who believed they were less active than others were up to 71 percent more likely to die in the follow-up period than people who thought they were more active than their peers.

“I was quite surprised about how consistent and how large these effects were,” says lead author Octavia Zahrt, a doctoral candidate at the Graduate School of Business. “Even many years later.”

Zahrt was inspired to explore this phenomenon by her own experience coming to Stanford from London.

“I always used to feel really good about my physical activity, and then I came to Stanford, where most people are super-fit and healthy,” she says. “So suddenly, in this environment, I started feeling like I wasn’t getting enough activity. I was feeling very unfit and unhealthy even though my activity level hadn’t changed.”

Zahrt and Crum offer a couple of possible explanations for the study’s findings. First, perceptions may affect motivation both positively and negatively. Those who believe they are more active may use that as impetus to exercise more. Conversely, those who believe they are less active may be more likely to remain so, triggering feelings of stress and depression, which may negatively affect their health. Placebo effects could also play a role: Those who believe they’re getting enough exercise may experience greater physiological benefits from their activities than their peers.

The researchers point out that while there’s truth to the power of our thoughts, this doesn’t mean behavior is unimportant. Physical activity continues to be a crucial determinant of health. “Our mindsets aren’t limitless, but we don’t yet know where those limits are,” says Crum. She and Zahrt are conducting further research in an attempt to measure health improvements among people who think they are active.

Their recent study was correlative, meaning it does not prove that perceptions of inactivity cause premature death. But Zahrt says it should encourage people to recognize when they’re physically active in their daily routine, whether that’s walking to work, cleaning the house or taking the stairs. •