Parks and Recreation:
Community Champions for Healthy Lifestyles
Click pictures to link to original articles.
"Nature is fuel for the soul!
Being outside makes people feel more alive." 
concludes a series of studies published in The Journal of Environmental Psychology
"Studies show that spending active time in the great outdoors is good for the mind. 
Humans have a deep-seated need for contact with nature"
"Group nature walks are linked with significantly lower depression, less perceived stress and enhanced mental health and well-being,"