What, exactly, does it mean to be an adult?

2013. The year my friends (and I) will be turning 30. That means we're adults now, right?
Sure.
But, um, when will it *feel* like we're adults?

I've wondered this for a long time. I thought the feeling of adulthood would come when I graduated university. When I got married. When I moved out of my parents' house. When I got a job. When I got a house. When I got a car. When I had a baby.
I mean, these are all clearly things that *adults* do and have, right??

Yet here I am, at age 29, still feeling ... well, not really like an adult.

But 30 is approaching. Have I missed an important step? I've been giving it a lot of thought.

I posted several years ago about Ikea furniture vs. real furniture, and wondering at what point in life people make the switch. Guess what? I'm there. Didn't even really notice, because it was a gradual transition. But I'm now at the point in my life where I'd rather have a nice, hefty piece of "real" furniture than a cool, build-it-yourself piece from Ikea. (Side note - don't get me wrong - I still love Ikea: I spent FOUR GLORIOUS HOURS combing the Ottawa Ikea this past summer with my best friend, both of us dreaming of owning so many of the cool and amazing things there)

So maybe adulthood isn't a "yesterday you weren't, today you are" condition, like graduating, moving out, getting married, having a baby, etc. Maybe adulthood is a journey, an accumulation of responsible habits. Outgrowing the need to be told what to do and just doing it of your own accord because you know it needs to be done. (Note: I don't actually have all of these mastered, but I sure am working on them!)

Grocery shopping for healthy food instead of frozen pizzas and egg rolls
Keeping a spare can of gas in the shed for your snowblower
Putting rubber mats in your car in the winter to save damage to your regular mats
Washing the dishes regularly
Keeping track of and paying all your bills on time
Taking out your shovels before the first snow of the year, putting them away when winter is fully over
Washing the dirt and grime off of your house siding
Mowing the lawn before you have a backyard jungle
Refilling the ice tray
Keeping your steps nicely shovelled / salted
Getting enough sleep
Painting / staining your steps / deck every year or two
Never missing a garbage day
Flipping / rotating your mattress every time you change your sheets
Cleaning the bathroom before the grime appears
Having spare lightbulbs in the closet
Being able to make supper out of random ingredients you find in your fridge
Taking care of your body / going to the doctor for yearly checkups

...and, truly, the list goes on and on.

I look at my neighbours across the street. They're in the almost-retired age bracket, and they seem to have it all figured out. Of course, I juge this by the fact that they have a nicely-tended yard, their Christmas lights get put up and taken down at appropriate times of the year (as opposed to ours, which have never been put up. The first year in our house, we bought the lights. The second year, we bought the clips for the siding.... we just had our 5th Christmas in this house :( Someday... someday we'll get those lights up for Christmas!), their driveway is always one of the first to be snowblown (and Mr. often comes over to help us out with our driveway, he's so generous and on the ball), they never miss a garbage or recycling day... I wonder how long it took them to achieve this perfection? I'm tempted to ask them. But probably won't. It's exactly the kind of inappropriate question I used to ask in my youth but like to think I know better than to ask now, now matter how curious I am.

So what makes someone an "adult"? What's on your list of "adult" behaviours / habits?