I started walking as a cub and then scout. I ascended the Brecon Beacons as a 12 year old and Snowdon at 14. I am sure many did this much younger than me. There have always been younger walkers. I think the older walkers are more noticeable as the general public doesn’t expect those in their 60’s, 70’s or 80’s to be out on the hills. Hopefully, when I reach those ages I will still be out and about, current injuries permitting.
I am sure that my other sports and fitness activities from younger ages is contributing to my current ailments: rugby, running, weight training, football, volley ball have all left their mark. Walking in the great outdoors provides just as much exercise, refreshes the soul and has less negative impact on the body. It just takes a bit more effort to get out and takes a bit longer.