I haven't quite reached that golden milestone myself (I rely on the likes of bobbi, sqad & doc to tell me how it feels.....), however I get more confidence & easiness with life as I get older. I can't say life began at 40, cos unfortunately my life between 41 & 44 went pretty pearshaped & crap, but I am 48 and love it.
Things are expanding, drooping, deteriorating - but I am so happy, have a great family , wonderful friends & realise what is important in life. And boy do I intend it to stay that way.