Horses adn people in poor condition. Trail riders cone into our area for recreation. Few can make over 10 to 15 miles in a day and heaven forbid doing that several days in a row. A well conditioned cow pony can do 30-50 miles a day for several days on reasonable terrain.
I would have no problem with 30 miles a day except for one small item.... my butt would fall off, and I'd never walk again.
Riding a horse is truly something you need to do on a regular basis to do it well over a long period of time.
Same with bicycles, btw. I recently got a bicycle for local trips and blithely headed out to the grocery store, a 4 mile round trip.
Since it had been 35 years since I'd been on a bike, it quite earnestly kicked my @$$.
I can do the ride today with no problem, but you don't just wake up one day and do it.
/johnny