The visit to the doctor included a bit of information that was interesting. He said studies have shown that walking 30 to 45 uninterrupted minutes is just as good as, or better than, running. I certainly think it is better for my joints.
He said strolling is fine. But actually, short, quick steps give me "very active minutes" on my fitbit, and I feel better than when I stroll slowly. It isn't always easy to get past the "stroll." I am trying, though.