There are lots of women over 40 going back to school and changing careers, just because you're 52 doesn't mean anything.
You say you've taken good care of yourself, you look early 30ish (and I'd assume you must feel that way too) then you shouldn't hesitate.
After all, look at Goldie Hawn, Kim Bassinger, Cheryl Tiegs, Christy Brinkley... all are between 50 and 62 years old.
My uncle is like you say you are, looks like a slightly aging adolescent and started in a new field, carreer, whatever you want to call it with the government in finger-printing (he's a retired naval officer) and he was in his very late 50s or early 60s !!
So go for it girl. You'll do alot better than those who relegate themselves to just sitting around getting old and just waiting to die.
Good luck, I'm sure you'll do well !!!