I remember a guy I worked with when I was about 35 -- he'd just turned 45 and was saying he was in the best shape of his entire life, pumping iron, running and working out. He said when he was at my age then (35) he would never have been able to keep up with his teenagers the way he was able to at 45.
I can say that today at 45 I am about as fit as I was in college, and many ways more so. It's not about the numerical age but how you feel <at the risk of sounding like another cliche>
Now if I can only get my emotional health back in order...
