Can I hop on my soapbox for a second? Of course I can. Query: are you over the age of majority in your place of residence? If yes, then you are an adult.
I know, you’re not an adult adult, not in your head. Neither am I! It seems like only yesterday I was 16, making bad (mostly fashion-related) decisions and not watching my smart mouth, and now here I am – home and dog-owning, overseas-moving, married lady with at least 8 white hairs (white! I hope I get a cool streak). I totally feel like an impostor a lot of the time – in fact, so does everyone, and it even has a name.
But the thing is, even though you (by which I mean I) don’t feel like an adult, you are. You have adult responsibilities like voting and going to the dentist and hopefully doing work that’s meaningful to you, but if not, at least paying your bills and eating your veggies (at least eating your veggies!). You aren’t an extended adolescent. You won’t be handed a manual and a Volvo on your 30th birthday and told that now you should start acting like a grownup. Are you not acting like a grownup? Then you’re wasting your life.

not an adult
An important clarification – acting like a grownup is not boring or lame. It doesn’t mean spending weekends pressing your pants (do people iron anymore? I sure don’t) or doing taxes. It means taking ownership of your decisions and your actions, of grabbing onto your life and saying a resounding “fuck yes!” and starting to live it. Is your ideal life working as a barista and skateboarding? Awesome! Own it, and please pull me a delicious macchiato, you caffeine wizard you. But if it’s not, don’t while away your youth behind that steamy espresso machine, telling everyone waiting for a drink that you’re thinking about going back to school as pumpkin lattes turn to iced coffee.
Another nice thing about being a grownup is that you can have pancakes for dinner, or drink mimosas on Sunday morning, or move to France. The catch is that you have to make the pancakes, not drive home from brunch, and be solvent enough for plane tickets. Sometimes the mechanics of your grand scheme are, admittedly, concretely un-fun, but the payoff, be it flapjacks or crepes, always tastes that much sweeter when your plans come to fruition and you can say, “I did this.”
So scratch your lottery ticket, finish your beer, and accept that, while being a kid was fun, you don’t have a time machine, and adulthood beats the alternative.