mountains is going home; that wildness is a necessity; that mountain parks and reservations are useful not only as fountains of timber and irrigating rivers, but as fountains of life. John Muir 1901
As part of studying mindfulness I have also been reading about the health benefits of nature for children (and adults). The NationalWildlife Federation has a very informative slide share on the topic.
Spending time in nature can help prevent and alleviate mental health concerns. Read this interesting study by beyondblue called "Beyond blue to green: The benefits of contact with nature for mental health and well-being".