I've always looked older than I was but on the whole I'm told I'm healthier than most women in their late 50s.
I would say the key thing is keep moving. That's easy for me since I have an active job and live in a place where I can walk everywhere-and since I don't own a car, that's how I mostly get around. It also doesn't hurt that I love vegetables and can no longer tolerate most sweet things.
I've also done weight training since I was in my teens.
Things I would tell my younger self: don't overdo it with the heavy lifting, don't starve yourself to lose weight, and for the love of the Flying Spaghetti Monster don't stress yourself by trying to please people that you don't like anyway.