I believe age doesn't define anything, at all

That's because you're young.

I've worked as an aged care worker. Old age robs people of their abilities, independence, spouse, social connectedness and friends. The majority of the very old are on antidepressants to mask the depression that comes from loss and grief.

Now that I'm a baby boomer approaching the threshold of old age, most of my friends and acquaintances are in the same bracket. Some of us have already died. We talk about the changes we experience.

The ideas that "age is only a number" - or that "you're only as old as you feel" - are two of the most ridiculous sayings I've heard.

They may sound like clichés to you but they weren't around when I was young. They are recent inventions that have taken off and become fashionable and they're euphemistic lies.

Wait till men turn their eyes away to pretend they don't see you,
till people consider your age a liability when you apply for jobs
or till you have arthritis and shaking a hand means crushing pain.

Wait till you discover that all your wisdom makes little difference because you no longer have enough time left to make the best use of it.

Appreciate and make the most what you have now.

Age is actually a thing. You feel it when you get up in the morning. You feel it at night. Systems start to break down and you can't see hear or do things you definitly did in your 20s. You can only strive for the best version of yourself you can be, but there is no pause button, no going back. Even if you pretend, that number is still there on your face and you will be marginalized for that.
It must be accepted and made to work and that can be done...but forgetting the number doesn't stop the hands of time. It comes for you anyway!

All I know is I always tell people I'm ten years older than I actually am.

See; people have it backward. I learned that from my grandmother.

I asked her once; "Maw Maw; how come you always tell people you're 85 when you are really 75?"; and she said; "Cuz I look pretty good for 75, but I look amazing for 85!"

You can't have experience and understanding of everything when you're young. That's where the cliche comes from.