Played fastball up until 2 years ago. Played it for like 30 years. I stopped because of a shoulder injury that really affected my throwing. No strength or speed throwing anymore.
I've played in a few volleyball leagues too & pick-up basketball. I prefer team sports over individual activities. You make a lot of friends on both sides of the field. It really helps you form a community.
It was also just fun, sated the competitive juices, and I actually trained for it all year. Not in a gym just on my own doing squats, push-ups, sprints, light jogging, etc. I was mainly a catcher, but also played outfielder to give my knees an occasional break.
It kept me motivated to stay in shape.
Which has been a bit of a problem since I dropped out. I tend to like outdoor activities over indoor, so hiking is my go to exercise now, but not a lot of socializing involved in that.
It's also really cost effective. Running shoes, baseball hat and glove is all you need, although some guys bring their own bat, I just used the team provided ones. They were all good quality. Cost to join is usually pretty good too.
You don't get too many fastball leagues these days, it's mainly softball, slo-pitch or 3-pitch.