I've hated this phrase for a long time - in part because someone once told me I wouldn't make it once I entered the "real" world. (Look at me now, beeyotch.) I guess the thing that bothers me most about it, though, is how the phrase typically is used toward kids.
Now that I'm in this strange realm called "adulthood," I really and truly don't get how people could possibly forget what it was like to be a kid, because I still know it as clear as anything. Children are just like adults, but they are clean slates. They are learning about the world around them. They are not separate from it; they are immersed in it.
The only thing that might separate them is the importance of play in their lives. I would wager that play is just as important to adults - but in different forms. Rather than using our imaginations to act out our make-believe, we use them to conjure up images in books. We use them to believe for a brief time in the fantasy world on a TV screen. We use them to consider what the future might hold if we make certain decisions.
Just because a person is optimistic doesn't mean a lack of awareness about obstacles and reality. It means that person has something many people have forgotten. It means an inherent belief that human nature is about goodness and love rather than war and backstabbing. Who are we to determine what a person's outlook on life should be?
Sure, teenagers don't pay bills. They don't have full-time jobs in high school (for the most part). They may not have a household to run. But the world is all around us - no one is free from its influence. Kids still feel pain when friends suddenly ignore them. They have hearts that can be broken. They feel empathy for others who feel these things. Those younger than us are not separate from the world merely because they are in school and have not yet inherited all of their parents' worries. What a ridiculous notion.
There is only one world, and we are all in it.