I have a theory that once we're adults, our brains only update our ages every few decades (or if something happens to our bodies that our brains can't lie to themselves about). So our minds think we're teenagers until we're in our thirties, or twenty until we're fifty, or forty until we're eighty. It's an evolutionary thing to free up brain power for more important stuff like dealing with doctors' receptionists.

I am not a scientist.🤣