I started riding in '76 after knee surgery on the advice of my surgeon. I found that I enjoyed it so much, I ended up with a touring bike (Romic, set up for multi day bike camping) and even dabbled a bit in some racing (custom Raleigh.) Then, for reasons I can't remember, I sold them both (still kicking myself over that) and bought a motorcycle. Good for the ride, not good for exercise. Heart attack in my 40s put me back on an exercise regimen, and back to cycling it was.
I can't do the distances I used to ride, as my knee now sounds like an old, rusty ratchet wrench, nor am I anywhere near 'racing speed', but I manage to keep my heart rate where my cardiologist wants it during exercise (okay, sometimes on a hard climb or a sprint zone in a club ride, my HR alarm on the Garmin goes off.) I used to do a lot of solo riding, but there just seems to be too many distracted / clueless / aggressive drivers now as compared to my touring days.
I got clipped a few years ago and ended up in the ER. Luckily, it was just road rash, a bashed helmet (which did it's job - the CAT scan of my head found nothing - well, nothing bad, anyway!), a good sized chunk of skin missing from my bad knee, and 12 stitches in my forearm. Had it not been for the one other driver on the road that morning, it would have been much worse, as the offending driver tried to drive off without stopping. The second driver chased him down and stopped him after checking to see if I was seriously hurt. Consequently, I only ride with a neighbor of mine, who still works during the day (I'm retired) or with the club on club rides, which isn't often enough. A lot of the club rides are well above my average speed, and distances / climbs only a migrating mountain goat would love. Thankfully, I have Zwift. Almost 2400 miles indoors so far.
I do love checking out new areas, having moved here with my wife to the Upstate (SC) when I retired. I'm looking forward to next spring, when I'll be taking a trip to Lowcountry for an organized ride. 43 miles, and the steepest grade is under 2%. I leave my driveway and hit a 7% hill to get out of the development!