If you want to improve your little grey cells and also make yourself happy, get yourself out into nature. Write yourself a “green prescription” and take a walk outside, in a park, forest or woods. Kuhn and colleagues report that “A whole-brain analysis [conducted via MRI] revealed that time spent outdoors was positively associated with grey matter volume in the right dorsolateral prefrontal cortex and positive affect, also after controlling for physical activity, fluid intake, free time, and hours of…