You've probably seen the story floating around of the 100 year old cyclist who set his speed record -well he's out to break his own record :-) Breaking it again!
I guess if I could still ride at that age, I'd be pretty satisfied with breaking my own record as many times as possible!
This also reminds me of a guy I met on a new years day ride - he was 76 and wanted to get the jump on his arch competitor at the local criterion (who was 83!). It really boils down to the saying: you don't get old and stop moving - you stop moving and get old.
and for some further inspiration: Check this out
Have fun and get out there and ride your damn bike!