Maybe I'm an odd duck, but a few years ago I found inspiration by trying to do my age in push-ups. I was 56 at the time, and when I realized it might be possible, I could do ~20. Just kept working at it until I did 56 in a row. Sometimes a tight focus like that can help. Or how about pickleball? Not my thing but a lot of people say it's fun and not too hard on the body. Just tossing a couple possibilities out there!