I'm 62, and having a blast. Helped do some system bringup a few days ago that brought back memories of "lab time" in the 1980s, though we get firmware onto boards with tens-of-megabit downloads now, instead of burning (literally) half a dozen EPROMs for every attempt. Things have improved a little!

Firmware worked on the new board, the very first time. I consider that a career capper. :-)

I figure I'll go until I'm 70 or so. We'll see.