I also have reached the Ultimate Answer to Everything (42). I suppose the only really noticeable thing---other than having weird pains in places I never did before---is that I just really don't give a crap anymore. Fads? New music groups? Celebrities? Don't care. Really, really don't care. I do what I want, know that right is right and wrong is wrong, and if I think someone is an idiot, I no longer feel the need to listen to their opinion for fear that they might not like me if I didn't.
I don't care about Facebook, I don't care what my neighbors are doing, I don't care about not having or getting "the latest thing." I do what I want, I say what I want, wear what I want.
In my twenties, I cared. I felt bad all the time because I was so out of it. I was ugly, dressed badly because I wanted to cover up my weight, wasn't popular, and was SO not cool. Now I look people in the eye and say, "I'm a nerd, a total geek. I don't drink, I don't like sports, I don't believe in God. I like Star Trek and Doctor Who and board gaming. I wear what I think looks good on me and what's comfortable."
The opinions of the rest of the world, frankly, mean fuck all. I can laugh at my own stupidity (so I laugh A LOT), and have no problem just walking away from people who bring me down. That lesson took me a long, LONG time to learn. I'm OK being alone and I'm OK being with other people. I wish I had learned that much sooner.