When I met him he was age5, and now he is a college student, and he can carry me!? Most people said that time is so fly but that's true, which means my brain got aged. I just saw TV show which research how come people are feeling time so fly as increasing aging.
The answer was "The spark joy", we are less spark joy feeling as aging because it's already experienced, excitement and joy feeling makes you feeling "no time fly", and somehow makes you look young! I love to keep in mind as always "spark joy" moment.