Sure, when I realize that the first Shrek movie was made almost 20 years ago, or that all of my students were born after the 9/11 attacks, or other events that point out how quickly time has passed, I feel a little out-of-time. Yet I don't think of myself as old.
I remember thinking that people in their 40s (let alone mid 40s) were ancient. Now, I think of myself as still in the prime of my life. It might be that I'm generally in better health than I was a decade or two ago (although that can change if I don't start exercising again). It might be that I still have older friends and relatives who are still going strong.
With the Lord willing, I still have many years ahead of me. I pray that I will continue to enjoy them in good health and with a youthful outlook. After all, I have a granddaughter who I want spoil.