For experienced outdoorsy people, it can be easy to think that walking is the simplest activity in the world. I’m a prime candidate for this; a middle-class, white, bearded man who grew up in an active household near hills, and who now owns more gear than I can squeeze into my house. I have heard enough comments along the lines of “But you just need boots, a coat and a bus fare” and “We’ve a right to roam so there are no barriers” to know that some people struggle to understand why many young adults don’t feel the outdoors is…