Just how much you think leg day at the gym will leave you limping actually has some real performance impact, according to German sports science experts.
Researchers from the Department of Sport Science at the University of Freiburg have discovered expectations around fitness play a part in how full on exercise is perceived, AAP reports.
With internal self-talk around exercise also a factor, scientists say their findings demonstrates the placebo effect extends to sport - and could actually play a big role in tackling obesity.
"Negative affective responses, in turn, decrease long-term exercise motivation and participation," they wrote.
"If one wishes to counteract the detrimental effects of a sedentary lifestyle, it is thus important to understand factors that affect perceived exertion in exercising individuals."
Psychologist Hendrik Mothes and his research team studied a group of 78 men and women aged between 18 and 32 who were asked to ride a stationary bike for 30 minutes.
Before the task, they asked participants about how how athletic they felt, and asked them to wear a compression shirt made by a well-known sporting brand.
After being assigned to different groups, they were shown a short films which either spoke of the positive or negative health effects of exercise, which was deliberately designed to alter their expectations.
During the actual 30 minutes of cycling, the participants were asked to rank the level of strain they were experiencing.
Published in journal PLOS ONE, the findings showed those who found the activity easier to complete watched the video with the positive message, and with higher self perception of athleticism leading to higher results.
However positive results didn't help participants who didn't think they were athletic. Researchers found the compression shirt only affected the participants who felt they were athletic.
Mothes said: "Merely the belief that the shirt would help, did help the 'unsporty' subjects to have a lower perception of strenuousness during the exercise."