In a philosophical sense it depends on what you you define as old. Is it a feeling to you, a state of living so to say, or do you look at the biological factors?
We could also say, how long do you see yourself as 'young' or 'in your youth'?
Sociologist are constantly debating on how long someone can be defined as 'youth' /'adolescent'.
Some are taking biological factors as the measuring focus and will tell you that adolescence ends as soon as you've finished puberty or after your brain is fully developed (18 ~25 years old).
Others take social indicators like managing your life independently, moving out, having finished a primary education that allows you to go to work and earn a living etc. Some of those definitions adolescence can last up until the 60's.
I wouldn't worry too much about that, sure I've also been getting older, but that doesn't mean I do less stuff, maybe I do different stuff now.
I for example don't go partying that hard anymore, I couldn't even if I wanted to because I know if I'm out on Saturday until sunrise I'll run around screwed up at least until wednesday, which I can't afford since I have another degree of responsibilites to carry now that I'm older and my interests also changed.
I'd say enjoy your life regardless of such labels, just keep being active and pursueing goals
