You'll probably feel the same way at various intervals in your life. You're just old enough to start to understand that you are mortal, but you'll get reminded of it off and on for a while.
For example, someone recently started working in the same place as me. I remember when their mother was pregnant with them. That made me feel older.
I had an odd conversation with someone about bunny rabbits and evil a couple of days ago. I referred to the rabbit in The Quest for the Holy Grail (with big, sharp pointy teeth!) and they had no idea what I was talking about. It was like a reference to a 1950s film for me.
Then there's the physical things. My left knee's a bit knackered. Minor injuries take longer to heal. You start to notice these things at ~40 and the gradual degradation of your body really slaps you in the face with your inevitable death.
But I'm a lot wiser than I was 20 years ago. Win some, lose some.