There is a new type of therapy. Yet it's really one of the oldest healing arts. It's called Ecotherapy. For more, see "The Nature Cure" from the October 2015 The Atlantic.
One physician, Dr. Robert Zarr, created a website, DC Park Rx, that is a community-health initiative. With this, he can write a prescription for his patients to spend a healing day alfresco.
In an 1862 issue of The Atlantic, Henry David Thoreau praised the vigor-inducing virtues of walking in nature: “Think of a man’s swinging dumbbells for his health, when those springs are bubbling up in far-off pastures unsought by him!”