I'm sorry but I laughed when you said that you are starting to actually feel old. But I get it! I did too when I turned 25 and when I turn 35. I didn't feel any of that much later until recently when I've had all kinds of changes happening so suddenly. But in retrospect when I talk to people that are 10 years older than me, I get some pretty good perspective. I keep thinking when I'm 60, I'm going to look back at 49 as a young chicken. So I'm trying to savor every moment.
If you think in the perspective of what being 10 years older than you are now, and what you will be thinking that you wished you had done than or what you might appreciate about when you were at that age. Does that make any sense? Just another perspective.
And depending on how you take care of yourself, you could even end up looking 10 to 15 years younger than other people your age. I think I looked older 9 years old than what I do now. Not just physically but even mentally the way that I carry myself.