I do this stuff for a living at the moment...!
I suppose it may have to do with the degree of autism. The people I work with at the moment, are deeply autistic/coupled with very challenging behavior...their vocabulary is limited to a maximum of some 25 words...or none...not even sign language.
I find that textures (tree bark, moss, sand, etc.) and walking in different types of terrain are some ways to communicate (with oneself and others) and to enhance some sort of "self perception" and feelings (emotional and body)...(?)
Some go bare-back riding on horses...also swimming...but these seem more labor intensive and costly in my opinion...compared to "off-road" activities
The problem is, that the guys that I work with have more or less no other ways of communicating other than grunts, whoops, puffing, biting and other acts of violence...so there really is no manual, per se...It`s more like a process of trial and error...
I find this job more worthwhile though, than any other that I`ve ever done before...however, six months from now, I`ll be changing profession.
Marko