I wasn't aware of age having a "feeling". I honestly can't say I feel any different today than I did 30 years ago... when I was in my 30's.

I used to (20 or more years ago) have more arthritic discomfort than I do now. And there was a period when my muscles appeared more elongated (a sign of ageing) than they do today. But there is no mistaking me for a much younger man. I'd guess that being healthy and fit feels "normal" or youthful. And maybe feeling ill or in poor condition due to fitness or poor diet relates to feeling "old".