Stages of Involvement in Professional Organizations

My observations after finding myself, inexplicably, as one of the two oldest individuals at an industry function last week:

Your 20s
I'd be happy to do that - and that, and that, and that.

Your 30s
I'd love to, but I'm already committed to doing something other than that.

Your 40s
I encourage my people to do that.

Your 50s
Why won't anyone ask me to do that?

Your 60s
What is that?