According to the placebo effect, your mind has incredible power to influence your body. If you don’t believe us, this study is proof.

Researchers at Harvard University gathered a group of hotel housekeepers who didn’t consider cleaning to be exercise, though the job is in fact highly active. Half of the 84 women were informed that their work met the Surgeon General’s recommendation for daily exercise, and learned how many calories their tasks actually burn. The other group received no information.

Over the course of a month, the “informed group” reported that they exercised more (though their workload didn’t change).

And the real kicker? The women’s physical fitness improved to match their perceptions. They lost two pounds, and they lowered their blood pressure, body-fat percentage, body mass index (BMI) and waist-to-hip ratio (WHR). Talk about a miracle mindset!