On the inside, I feel like myself, no specific age, but I am 65 on the outside. I tell the younger ones I know (20s and 40s) that when people get older, they are still the same person they always were. I don't mean they haven't changed throughout their lives, because many certainly do. I mean, see the person, not plunk them down into the senior citizen category without at least trying to get to know them. It is valuable to me to have friends in a lot of age ranges. I learn a lot from them, especially from one guy who spent 20 years on the trading floor - I like talking about investing with him. The others, I mainly get to experience different points of view, some of which I had when I was their age and solving the problems of the world seemed easier, and sometimes obvious. All these years the same problems exist, the younger ones are always surprised. And I think that they must think that older people lived their lives with their heads stuck in the sand. The world is just is complex as it always was.
I would feel more comfortable in a younger body. Mostly I don't like not being able to do things with the same speed and stamina I used to have. I don't like having health problems, but I'm used to it since I was 46 and had emergency double bypass surgery. I don't like thinking about getting another dog some day, and realizing I had better know ahead of time and for sure, that my daughter will take it when I die.
I don't like that some of my favorite authors have died, most from old age. I was reading a list of 100 most popular authors in the genres I like (on the Fantastic Fiction website), and I knew that some on the list had died, two after writing only one really great book. So I've been trying new authors so I don't get stuck with nothing but re-reads.
I feel old just when my body doesn't work the way it used to. I don't want to live forever, but I sure wouldn't mind reverting to my younger body with me in it, a 25 year old body. I would do a lot of things differently because I would still be like I am now with many of my mistakes learned from.