Mid-60's here. Running very slowly for 3-5 miles every other day now (walk 1-3 hours on the other days) and the writing is on the wall that I won't be running much longer. Everything is sore afterwards so I need a day of not running to recover. When I try to do quicker or longer stuff, I end up extremely sore or injured for a week or longer, so I don't do hills, striders, intervals, tempos, or longer runs any more. Running is not much fun on most days now - I only do it for the fitness benefits. I want to continue to be active, but I may soon need to find another sport, like cycling or something (tried swimming a while back, hated it.) It's just getting too damn hard any more.
Loved running, REALLY loved running, my entire life until about age 56-57 when it started to get MUCH harder every year. Ran lots of 100 mile weeks when I competed in college and was training 30-60 miles per week while competing until 42 years old. Disgusted with all race efforts in the year I was 42 and stopped competing - I had very quickly gotten much slower that year (don't know why, just age I guess) and my races were nowhere near any minimum standard I'd held myself to. It was not fun to race any more, but I kept training because I enjoyed running and how it made me feel physically.
I am grateful I can still run at all in my mid-60's. I am aware of only one other runner from my high school or college teams who still runs and he has the same complaints. I don't think he's long for running at this point either. I don't know how Ed Whitlock (RIP) did it - guy was a freak of nature and I have a ton of respect for his amazing accomplishments.