It is a pointless endeavour fearing something that is inevitable. Nobody likes getting older it's a tremendously depressing subject if you dwell on it but I see it as an utter waste of time and energy fretting over something you can't avoid.
At least getting old you can wind down, work less if at all and do a lot more of things you enjoy. When I trained at a local gym, my job enables me a lot of time off during weekdays so could train when gym opened at 9 and about ten older guys who were retired trained then and seemed to greatly enjoy themselves and seemed to have a good life