A positive mindset isn't just mental – it can trigger physical changes making you fitter, slimmer, more energetic and less stressed. It will even help you live longer

“OUR minds aren’t passive observers simply observing reality as it is; our minds actually change reality. The reality we experience tomorrow is partly the product of the mindsets we hold today.” That’s what Alia Crum told global movers and shakers at this year’s World Economic Forum in Davos, Switzerland. It may sound like New Age nonsense, but Crum, who heads the Mind & Body lab at Stanford University in California, can back up her claims with hard evidence showing the mysterious influence the mind has over our health and well-being.

Crum’s pioneering research was inspired by her own experiences as a child gymnast and college ice hockey player. “You can be the same physical being from one day to the next,” she says, “but your mindset can have a dramatic effect on performance and physiological capabilities.” She often wondered why. Then, as a psychology student, she read about the placebo effect and had a eureka moment: if our expectations can influence the effectiveness of a drug, perhaps something similar can happen in other situations, too.

Pursuing that idea, Crum and others have discovered that your mindset affects everything from your weight and fitness to the physical toll of insomnia and stress – even how well you age. The upshot is that two people could have identical genes and lifestyles but one can end up healthier than the other, thanks solely to their different thoughts.

Placebos are inert pills used in most clinical drug trials. The participants are divided randomly into two groups: half take the drug being tested, the rest, for comparison, take an identical-looking sugar pill. With no active ingredient, the …