Henry David Thoreau went walking in woods and fields more than a century ago and found the experience decidedly therapeutic. "I come to myself," he wrote, "I once more feel myself grandly related, and that cold and solitude are friends of mine. I suppose that this value, in my case, is equivalent to what others get by churchgoing and prayer. I come home to my solitary woodland walk as the homesick go home. I thus dispose of the superfluous and see things as they are, grand and beautiful."