What is old?

I don't feel 'old' when I am on my bike. I am turning 90 rpms, doing 18 mph and feeling good. As long as I keep pushing the pedals, I feel like I could go forever. Then I hit the hills and my cadence goes down, the gears go down - and the speed goes down. I work hard at it, but the amazing thing is, I have this feeling that I haven't really learned to give it 'everything' yet. There is still more inside this 61 year old body that isn't being used. If I just got a little more disciplined in my training routine, I know I could do more. As senior cyclists we can do a lot. Can we keep up with the 30 yr olds up a long hill, probably not. But is that necessary? Not at all. It is enough that we are out there, hammering hard.