Outside the Olympics and similar walking is not a competitive sport. Therefore, I don’t think any society’s definition of a long walk really matters. What is long to one person will be short for another. In fact, what classifies as long to a particular walker may vary with age, fitness and experience. In the past, 15 - 20 miles in a day was not particularly difficult for me, even if it included mountains, and much longer walks were quite common. Now, I am older, fatter and carrying some injuries, so 15 miles would seem pretty long. I hope to remedy these shortcomings in the future, so that I can readily take on longer walks again and so that my wife will be happy for me to be up high by myself again. (I haven’t found the fountain of youth, so my age is one thing that I won’t be improving). I would also like to be able to return to multi-day walks.