I feel pretty fortunate. Much like Redsfan, the main league team I've played on for 17ish years is pretty much the same team that's been playing together for over 40 years.
Lost and gained some people over the years, it's a team I got on that my dad was on before I was born (I'm 35 now). And as some have dropped off, other sons have joined in, it's really a family team. We all go camping together, grew up together really. My dad knew the coach and his twin brother growing up from elementary through high school.
I think of the original team there's still.... 6 guys? Half the team is in their 60s, a few in their 40s-50s, and then 5 or 6 in our late 20s-30s. Some got tired or busy, some passed away.
With everyone having family's and whatnot, it's really just easier to have 18ish on the roster. Sure days we suck we may only hit once per game, but we rotate in the field and all get some game time. Probably won't be too many years before some of the Founding Fathers transition to a senior league, when it does it all might fall apart, or me and my two buddy's who grew up on the team might sew together a group. No clue. But aside from the league scheduling, it's the best team I've ever played on. Won the league maybe twice through the years, but usually hang around the bottom half. Friends make it fun.
Edit: I will add that it's so much fun being on a team where we beat a bunch of ex-high school players with a team that half the players are over 60. Lol.