British researchers looked at ten various studies on the effects of activities performed outside in nature.  Activities such as walking, cycling and gardening had positive effects on the 1,200 people surveyed. According to Jo Barton, co-author of the study, “There would be a large potential benefit if people were to self-medicate more with green exercise.” The largest positive health changes occurred when people exercised in the outdoors.

The article, “What is the Beat Dose of Nature and Green Exercise for Improving Mental Health” can be found at the link  http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/es903183r