So I've reached my 46th year fairly unscathed. I've still never missed a
day of work, ever, and I'm rarely under the weather. In fact, I feel
great.

Only 46?
Don't even entertain those thoughts yet.
My CFI is 71.
The guy I just bought my plane from is 74.
Seems to me your health is just fine.
So what if you need bi-focals.
So what if you don't fly at night, or choose to avoid overcast days.
Just contour your flights to fit the conditions you are comfortable with,
and fly until you aren't *safe* anymore.

Adam

P.S. Sound advice from a guy who's going to be 30 next month ;-)