36, feel fantastic.
Same here, I feel awesome.
It helps that I exercise regularly (although I can't even attempt half the level of weights I could do in my 20's) and I try to eat as healthy as I can.
Also having a near stress free job helps. There's a lot of things that I would change if I could go back in time with my current knowledge. But for all I've been thru, I'm actually in a pretty good place in my life right now.
As for getting older, I do worry about it, but if things go well, I should be healthy and strong going to my 60's. Then we'll see what happens.