My hair is at the badger stage, and I'm basically bald apart from the back and sides (in hindsight I think I started losing my hair at around 19-21). I shave the whole lot off every couple of weeks these days.
I get white hairs coming through in my facial hair, I generally leave them alone unless they look particularly conspicuous (like when you get a thicker-than-average hair and it happens to be white).
Do what you like to your hair. I personally subscribe to the idea that ageing gracefully also involves accepting the aesthetic changes as they come. The only exception I apply to this is not wanting to look like my dad who is more than double my age, which is part of the reason why I shave my head, and partly because what the hell would I do with it otherwise?
While I think that my idea of 'accepting age gracefully' is less likely to result in me trying to relive my youth in some absurd manner during a mid-life crisis, I could see how it might actually encourage such a scenario, or someone or excessively tries to cover up the signs of ageing might do the same (though admittedly I don't see how that behaviour could result in them being less likely to have that absurd mid-life-crisis style I mentioned).