I worked full time as a senior chemical process engineer until the age of 75.    Helped to solve many complex problems.    When asked, I'm still doing a bit of part time work at the age of 77..    One of my hobbies is creative writing, either books or screenplays.     I think a key detail here is one's energy and fitness level.   (My deepest sympathies to those who become ill early on from no fault of their own.)     For the rest of us - listen up - I go to women's total body workouts in the gym which are very energizing for mind and body.   And I weigh myself every day.   Many of us in the Western World are too sloppy with our lifestyle and just waste away and become a liability to oneself and to others, much too early.    I think there is room for improvement..