What kind of a league do you play in ? To be honest I thought you were older. I stopped playing tackle football in my early 30's as well as softball too. Did you ever think of doing the reg park 5 sets of 5 routine ? The last game of football that I played was against a bunch 20 -25 years old guys, my friend who was 31 at the time got his nose obliterated that's when I made my mind up to never play again as I was waiting for them to set his nose in the hospital emergency room. GOOD TIMES 
I do do the Reg Park 5 x 5 as well - actually alternate that with the 6 x 2 type stuff. Didn't know that was a Reg Park thing.....cool.
I play in 45+ and 50+ baseball leagues, but they also have 58+ 65+, etc..
It is mostly ex-college players who never stopped, sprinkled in with some guys who played even higher. For example, Oil Can Boyd used to pitch, etc...
And I can say with total honesty there are guys who are doing amazing things at ages people can't comprehend. Seen 380+ foot HRs from guys over 50, diving plays, pitchers over 60 going 9 innings and 120 pitches with no walks, etc. Seen a 72 year old guy hit one off the fence.......it's this cool subculture that nobody cares about, but it means everything to those playing, and they play to win. There's even big time tourneys in Fla, Az, etc....It's a thing.