There's a great book called Bird Therapy - https://www.goodreads.com/book/show/43804073-bird-therapy - where the author talks about how birdwatching helped enormously with his mental health. He talks briefly at one point about two runners who "birdwatch" while running, and who find the same kind of meditative peace that he does from a long walk with birdwatching points along the way. I've only just started trail running, but I find the mix of nature and running definitely multiplies the benefits of exercise and meditation rather than just adding together. (That is, if there aren't too many people around - I live in a relatively crowded part of the country unfortunately, so despite being surrounded by lovely countryside there are often quite a few people about!)
