I am 67 and used to be a runner. I stopped 5 years ago because of an unrelated back injury and surgery. To rehab and get back in shape, I bought a Peloton and really pushed it. And got into riding road bicycles near my home. Faster and faster.
I tried running again, but found it too hard on my knees and feet..
I now ride around 175 miles a week on the road, mostly with a group. Usually around 20 mph but with a few miles as high as 24 mph. I like pushing myself. And I mountain bike once a week on single track with my son.
Road bicycling is by far the easiest, with running and mountain biking being about the same. Because I fall riding trails, I probably shouldn’t be doing.
But it’s fun and I like spending time with my boy.