When done sparingly, it looks extremely natural -- even up close and in person. My brother's wife and mother-in-law look about twenty years younger than their ages.
We've all probably seen some people who look like botox disasters or plastic surgery disasters with unnatural looking faces, but what you don't necessarily notice is all of the people doing it in a more low-key way.
Another thing I haven't seen mentioned is facial moisturization for men. I get the impression that men rarely used to do this and that it's still somewhat rare. Trust me: it works. People are generally surprised by my age.
People have mentioned reduced sun exposure and physical labor. I don't know that I buy this. I don't think the cast members of Cheers were exactly toiling in the fields all day long.
Reduction of smoking is definitely a factor.