People who do no exercise cannot comprehend what goes on with people who do.
When I first went to the rheumatology specialist in Southend hospital, we talked about exercise. This was before I had taken up cycling again. I was doing a fair bit of walking, well in excess of the Government recommended 10000 paces per day.
To me, a moderate walk is 5 miles and takes me a little over 2 hours on the flat and in good weather. After 8 miles it becomes long-ish, 10 miles is a long walk. My son in law would disagree, but he's a maniac who walked from JoG to Land's End, some days covering more than 30 miles.
The rheumatologist told me that 2 miles should be adequate - which is about what I do every morning with the dog when we go to the park. Totally inadequate if you want to do a proper day's walking. Last week, almost 3 years later, we climbed Cader Idris. Not the most challenging of peaks, being totally non-technical and only about a 6 mile walk from the YH and back, but we did it without a lot of difficulty, apart from the periods in which we couldn't walk but simply had to brace ourselves against the wind. My knees were playing up at the end. That wasn't arthritis, though: it was the tendons at the back of the knee having cushioned my enormous bulk down 2500 feet of descent, and a gentle bike ride the following day sorted them out.