I've been reading Roman and Greek mythology. Zeus (Jupiter) was probably modeled on a guy in his prime (these days, that can easily in the 50's). At 50, if you've taken any kind of care of yourself (no smoking, prudence in boozing, and a work life where you have some autonomy or authority), you'll be building toward a peak in your 50's, probably at 62-65.
I'm stronger now than ever, and have discovered that I can intimidate younger guys because I don't give a sh-t about what my status is vis-a-vis them. I know who I am and what I can do. One example was at a Cake concert this summer, when a twenty-something dude tried to show off in front of his girlfriend, and take my little piece of ground in the front row. I knew I had been here before him, and didn't give in to his whining. Fortunately, his gf understood what he was up against, and pulled him away.
You've got several good years ahead, brother.