I agree. You should never retire to do nothing.
You may, however, reach the point where its time to do something else.
Retire when your personal projects don't leave you enough time to work for someone else.
I turned 66 last Thursday. I own and run 4 businesses, write a lot of paychecks and pay a lot of taxes.
I guess I am legally retired, but I’m not going to quit working. I’m just going to have one heck of a retirement party and then get up the next morning and go to work.