People who spend twenty or more minutes outside in the sunshine in the spring and early summer have more expansive and open thinking, Matthew Keller, assistant professor at the University of Colorado at Boulder, et al tell us in their research paper A Warm Heart and a Clear Head , and Barbara Fredrickson describes in her book, Positivity.
This exposure to the elements causes our working memory span to increase, so we can literally hold more thoughts in mind, a commonly held definition of intelligence.
So next time you need a pick-me-up and are gravitating toward a sweet snack or a caffeine hit, grab your coat instead and head outside. Your waistline and outlook will both thank you.