Twenty million people in the United States live with depression, says the National Institute of Mental Health. And that's just in the United States. A staggering amount live with it throughout the entire world. (MORE: Which Country Is the Saddest?) One potential method to combat the condition is to walk it off. Some time in the great outdoors has been found to enhance mental health, well-being and reduce stress. A study published in the journal Ecopsychology examined 1,091 participants who...