Feeling Old?

I am a couple years shy of 40. My husband is a couple of years beyond 40. The other night we discussed the fact that neither of us feel like our age. Both of us feel like we are somewhere much younger. He did not really specify how old he feels, but I know some part of me still feels like a teenager.
Its pretty strange. I really dont feel like a parent - although I have been one for several years now. Its weird to me to be all grown up like this. I feel young, but when I see 18 year olds now they look like babies. I wonder if everyone feels like that. I just hope I feel like more of an adult when I'm 64.