Age catches up to all of us, assigning a hard number misses the mark, good or bad. Personally I have an aunt in her 90's who is quite infirmed physically, but her memory and cognitive abilities are amazing. I am less in favor of age 67, more in favor of success in training and medical certification being the deciding factor. As for me, if 67 happens, I doubt I will want to continue past 65 (or less), but I'd like to go out on my own terms.