The sorts of examples given - queen, pope, Alex Ferguson, Ben Fogle, etc., are not in run-of-the-mill jobs. Many people, including myself, have done jobs that they don't particularly like or that are very physically taxing. They may well be thoroughly relieved to retire. That's not to say that people shouldn't pursue other careers if they wish and are able to. And, let's face it, many retirees are doing other unpaid jobs looking after grandchildren (and elderly parents).
Forgetting where you left your keys dies not mean you are “losing it”