bmcer,
I'm 70.5 and I also have people thinking I'm ten years younger...probably because I still have most my hair and have not gained much weight.
Still, I've found it weird that I now have to actually figure in my age with my athletic endeavors....which are modest. Historically I never thought a ride was "too long"...maybe it would take me a bit longer and I would have to bring extra water but never that I couldn't make it or ride three days in a row, etc.

Now I really have to consider those things and it's a bummer. I'm getting used to it but it makes me wish I had enjoyed and taken more advantage of my younger years. But I suppose almost all older people feel that way. Making your goals an improvement in YOUR metrics is a wise way to approach it for sure. Now where did I leave my prune juice?