If I was capable of knowing what I do now - 48 - it's just two years ago but that would have left me with enough time, to tell the most important people in my life at that time, what they meant to me. If it isn't possible for me to have that advanced knowledge - then I'm OK with my current age - after all I'm still alive.
Many years ago, I read that age 53 was usually the best year of a woman's life. I don't put stock in such broad theories but it turned out to be true for me. I like where I am now, as well. I don't think I'd ever want to be younger than 30 again, unless I knew everything I've learned since then.
Here's the thing... In many ways life has been good to me, in many other ways it's been a struggle. I guess I kind of appreciate where I am, and would only go back to an earlier age IF I could take my accumulated knowledge with me and not have to go through the crap again, but if I could -- somewhere just north or south of 30 would be ideal.