This was a question and response on Quora and I’ve added my own response to it.
“Why do people in their 60s think they are not old when they are about 85% through their lives?
I turned 70 last year. If I lived in one of the countries where old people are revered — some, like Korea and France, even have laws protecting them and forcing their children to visit them — I might dare to think I was old. But I live in the United States, where old means feeble in body, unattractive if not downright ugly, on the way to dementia if it hasn’t set in already, and unable to contribute to society in any meaningful way. I refuse to be any of that, at any age.
Also, I don’t feel old. Last time I saw my doctor, she said I’m in good enough shape to live another 30 years. So maybe I’m only 70% of the way to death, and maybe something or someone will kill me tomorrow. Whatever. I know how to be young, and I know how to be middle-aged. I have no idea how to be old, so I’m not even going to try.” https://www.quora.com/Why-do-people-in-their-60s-think-they-are-not-old-when-they-are-about-85-through-their-lives

I am turning 70 in about a week. This OP doesn’t seem to understand how aging works. While I “feel” old (and most of that is due to a car accident and multiple bouts of cancer, not so much getting older), I don’t “think” old.
While the body ages, in most cases, the brain doesn’t. A lot of us think the same way at age 70 as we did at age 20. So why should we think of ourselves as old?
I still like the same music I did while learning about new forms of music. I still like fashion. I still like culture. I still like food and recipes. I still like learning new things.
Why do younger people think that anyone over the age of 60 is just sitting in their Lazyboy recliner watching Jeopardy, or worse, sitting in a rocker just waiting to die?
No… We are going to concerts rocking to classic rock (remember Robert Plant is 72), we are writing books, we are running businesses, running in marathons, cooking meals and designing and decorating houses and fashionable clothing, and while some of us are happily retired, we are still questioning things in society, protesting wars, looking out for the environment, challenging religious teachings, and some of us are running for president and winning (Joe Biden is 78). My dad is turning 92 in January.
So watch who you point fingers at and remember one important fact. Unless something happens between now and then, you will soon be us. And you will be frustrated with young people who question your age.