I've just come across this new term and find that it fits me perfectly.

In my youth I was quite shy and could be put down very easily but since reacting that magic 60 I find that my personality has undergone a complete change.

I won't be pushed around. I can't stand rudeness or inefficiency. I complain - fire off emails (to local council and companies that upset me) - write to newspapers/magazines and I'm not sure where the new me has come from but I'm finding it very liberating.

I've become my own person at last.