Certainly kids keep people young, but they are a "symptom" of what keeps a person young I think. When you think about it a little the reason kids keep a person "young" is that being w/ a child is vicariously discovering again why life is so exciting, interesting, challenging, etc. So that great feeling of discovery rubs off. Another reason I feel that this "sharing" things new feeling is so much a part of being "young" is my memories of my grandfather. He lived to be 99, and was fortunate enough to have good health pretty much until the end. My mother told me that he once said that as his friends his age died he found that he could just sit there and get lonely or get out and meet new people--generally younger who shared some of his interests. He then learned to enjoy some of theirs. When he was at the end, many of his friends were thirty even forty years younger than he was. He kept a lively interest in everything, never stopped learning. He always had something going on--he taught a lot of people one of his passions, making wine.
My father was much the same, dying at 95, his friends were in their 70's down to people younger than me. Again, he always shared his interests with them--hunting, fishing and food--and they shared their interests with him. Kids do keep you young as do new friends. But essentially its actively keeping an interest in life and learning, discovering and appreciating new things--maybe a play on the political statement says it, Ready of Change--it keeps you young, IMO.
