Oddly, I'm experiencing something of the opposite as I age. My serum testosterone levels are much lower than they were a decade ago, and significantly lower than even three years ago. As a result, I'm feeling less physically strong, though the process has been so gradual that I haven't had any all-at-once noticing moments like you describe.

Some older men take T as a supplement, but I'm not sure I want the side effects, to be honest. I think natural aging so far is agreeing with me, though I don't like finding that boxes are harder to lug around than they used to be.