Stanford researchers Octavia Zahrt and Alia Crum
found that U.S. adults who believed that they were
less active than their peers died younger than those
who believed they were more active – even if their
actual activity levels were similar.
“Our findings fall in line with a growing body of
research suggesting that our mindsets – in this
case, beliefs about how much exercise we are getting
relative to others – can play a crucial role in our
health,” Crum said.
Alia Crum, an assistant professor of psychology, and
Octavia Zahrt, a doctoral candidate at the Graduate
School of Business, analyzed surveys from more than
60,000 U.S. adults from three national data sets.
The surveys documented participants’ levels of
physical activity, health and personal background,
among other measures.
In one of the samples, participants wore an
accelerometer to measure their activity over a week.
Zahrt and Crum were interested in one question in
particular: “Would you say that you are physically
more active, less active, or about as active as
other persons your age?”
The researchers then viewed death records from 2011,
which was 21 years after the first survey was
Controlling for physical activity and using
statistical models that accounted for age, body mass
index, chronic illnesses and other factors, they
found that individuals who believed that they were
less active than others were up to 71 percent more
likely to die in the follow-up period than
individuals who believed that they were more active
than their peers.
Much of the study’s inspiration derived from Zahrt’s
experience when she arrived at Stanford.
Zahrt, a native of Germany who previously studied in
France and England, had stayed in shape by biking to
school and making occasional trips to the gym.
But at Stanford, Zahrt said it seemed that “everyone
was incredibly active” and perhaps she wasn’t
exercising as much as she should.
“Suddenly, I felt like I had done something wrong
all these years,” Zahrt said. “I felt unhealthy and
I was stressed about fitting more exercise into my
busy schedule. I really had a negative mindset.”
While taking a health psychology class taught by
Crum, Zahrt learned more about the effects of
mindsets on health outcomes.
For example, Crum’s prior research shows that the
health benefits people get out of everyday
activities depend in part on their mindsets – that
is, whether or not they believe that they are
getting good exercise.
In her 2007 study, Crum made a group of hotel room
attendants aware that the activity they got at work
met recommended levels of physical activity.
Through this shift in mindsets, the workers, many of
whom had previously perceived themselves as
inactive, experienced reductions in weight, body fat
and blood pressure, among other positive outcomes.
Zahrt wondered if many people, like her, had
negative mindsets about their physical activity
levels because of social comparison with more active
peers, and if this might be harming their health.
Those who are made aware of their healthy activity
levels – like the hotel room attendants in Crum’s
2007 study – can build on them and exercise more.
Those who deem themselves unfit are more likely to
remain inactive, fueling feelings of fear, stress or
depression that negatively affect their health.
The researchers also cite the established influence
of placebo effects, where patients who think they
are getting a treatment experience physiological
changes without receiving actual treatment.
In the same way, people who believe they are getting
good exercise may experience more physiological
benefits from their exercise than those who believe
they aren’t getting enough exercise.
“Placebo effects are very robust in medicine.
It is only logical to expect that they would play a
role in shaping the benefits of behavioral health as
well,” Crum said.
The researchers emphasize that the study is
correlational in nature and thus does not prove that
perceptions of inactivity cause earlier death.
However, other experimental research – such as
Crum’s 2007 study – does suggest a causal nature to
the link between perceived amounts of exercise and
“So much effort, notably in public health campaigns,
is geared toward motivating people to change their
behavior: eat healthier, exercise more and stress
less,” Crum said.
“But an important variable is being left out of the
equation: people’s mindsets about those healthy
In fact, a growing volume of research from Crum and
other labs shows that perceptions and mindsets
predict health and longevity, for example, in the
domains of stress, diet and obesity.
“In the case of stress, a thought about something
going wrong can make us sweat or shaky or increase
our heart rate,” Crum continued.
With sexual arousal, a simple thought or idea can
have immediate physical effects.
For whatever reason – dualism or a prioritization of
the material – we tend to ignore the fact that our
thoughts, mindsets and expectations are shaping our
Being mindful of and feeling good about activities
you do every day – like taking the stairs, walking
or biking to work, or cleaning the house – could be
an easy first step for everyone to benefit their
“It’s time that we start taking the role of mindsets
in health more seriously,” Crum said. “In the
pursuit of health and longevity, it is important to
adopt not only healthy behaviors, but also healthy
For more information
Perceived Physical Activity and Mortality: Evidence
From Three Nationally Representative U.S. Samples.
Mind-set matters: exercise and the placebo effect.