I’m in my 40’s and about to be married. My Fiancé and I bought a house last year. We have cars, jobs, pets and a mortgage. But we still still feel like we’re waiting for the grown-ups to show up and tell us what to do.
Over 50 on the outside, 16 on a good day on the inside. 
When my mother was in her early 80’s she said “You know, I feel just like I did in my teenage years, I just can’t do what I could do back then.” I turn 60 in March and I feel great, just like I’m in my 20’s but I can’t do what I did back then. lol. I joined the YMCA at the age of 22 and I’ve been hooked on physical activity ever since. I hope I’m active till the day I die.
I’m 49. I feel the same now as I do when I was 13. Either I was mature for my age, or never grew up mentally. I honestly don’t know which it is.
Yeah my siblings and I, three professionals and a slacker (ME! :P) all range in age from 33-41 and yeah all of us are kids. Especially together, we have snowball fights, who can do the best donuts/burnouts, try to scare the shit outta one another at our respective homes the list can go on and on about the things we do as kids would.
Yet during the day we all go to work, we all raise our children we all function like so called adults but it is just a mask we wear I think.
I often work in nursing homes and one of things I like to ask the residents is “how old do you feel” or “what was your favorite age” - because I get some interesting stories.
frequently, people in their 90s will refer to other residents as “those OLD people”.
I’ll be 45 in March and I just played in a bouncy house today. I’ll let you draw your own conclusions from that. : p
I had something like that happen to me when I was registering my eldest kid for kindergarten. I was sitting in the school lunchroom, filling out forms with all the other parents registering their kids, and I thought, “Shit - all these people are old. They must’ve waited to have kids or something.”
Then I realized that most of us were probably the same age, some of the likely younger (we waited until I was 30 to have kids). It was just surreal.
You are not alone, OP. I am 44 and yet I feel like the same kid I was at 18. It is very jarring to see images of myself and try to reconcile what that person looks like with what I feel like.
I think it has to do with having no kids, no pets, and nothing to really worry me. I haven’t had to really grow up. Plus, I didn’t do a lot of immature things at the age I should have so I feel they’re still fair game.
If there weren’t a weight limit (I have to think there is?) I would be in there too! I finally went on a trampoline for the first time at 30+.
No thanks, I just ate.
I’m 32, and I feel very much grown up. Sometimes I sit in meetings at work, and it cracks me up because they sound just like the faux meetings in movies (“Sven, you’ll have to run the numbers and finish the report before you fly out on Thursday…”). When I meet people, they treat me with some authority. I’m hitting those lifetime milestones left and right. Yup, this is my adult life alright.
I think part of it is that I grew up in a small family- just me and my mom. So I never really got this illusion that adults have all their shit together.
I promise, you would totally be okay. As a, erm, fluffy member of society, we had no equipment malfunctions while we all played.
I’m 32, and I feel very much grown up. Sometimes I sit in meetings at work, and it cracks me up because they sound just like the faux meetings in movies (“Sven, you’ll have to run the numbers and finish the report before you fly out on Thursday…”). When I meet people, they treat me with some authority. I’m hitting those lifetime milestones left and right. Yup, this is my adult life alright.
I think part of it is that I grew up in a small family- just me and my mom. So I never really got this illusion that adults have all their shit together.
even sven you grew twice as fast as us 
Just like a kid to doublepost. 
Tonight I sang at the top of my lungs to some old alt rock tunes that were popular when I was 16. That was 14 years ago. I usually crank the music as loud as possible on my commute.
I feel grown up. I grew up in my late 30’s and early 40’s. It didn’t happen over night of course, but over the course of a decade, as I grew comfortable in my skin, began to like who I am, recognized my strengths and came to terms with my weaknesses (a work in progress, eternally). I love what I do, and I do some things really well. Now in my mid 50’s, I feel like a well adjusted person who makes positive contributions to his community.
I feel the same at 34 as I did when I was 15. That is to say, I still feel like I’m the only adult in the room.
For me it’s both true that I mentally feel that I haven’t changed and that I sometimes forget my age.
I saw that there was a youth club near to my house the other day, so I had a brief “Yay cool…oh wait, I’m 33 years old” moment.