Dear Joliette, if it makes you feel any better, my youngest kid is older than you !
Actually 40, when you get there, is not so bad, you can still act like a Teenager and get away with it. Now I am well in to my 70's I get berated because my sense of humour is no more mature or sophisticated than that of a 12 year old kid ! I still laugh at Fart Jokes ! Also I get very pissed (drunk) sometimes, but, what the hell ?
I can be sensible and mature when I am 6ft under, in between, whatever age you are this applies : "Life is for Living, for Loving, for Laughing and for Enjoying."