

I’m in my early 60s and went from walking to jogging a couple years ago. I did it differently than you. My usual walk was about two miles, and I just started jogging the portion I could and walking the rest. At first, my jogging was only a couple blocks, but as I kept doing it, I got to be able to go further, a little at a time. My goal was really just to keep my heart rate up for 20 to 30 minutes and get some cardio.
So I’m there now. I jog a couple miles every other day. Takes me about 25 minutes, so I’m not breaking any speed records, but my heart rate is between 150 and 170 for much of it, so I feel like I’m meeting my goal.

I’m more of an SF person, but I really enjoyed the Raksura series, by Martha Wells, about a guy who can shape shift into a sort of dragon. I’m also currently rereading the Amber Chronicles, by Roger Zelazny, and it’s very good.
In case it helps any, I made a post with a giant number of spoiler-free short reviews of SF and fantasy books I’ve read over the last few years, and many of the books mentioned here are in them.