Draw the line?

Why do we always draw the line? When we grow up we stop doing many of the things that we used to do and enjoy as kids. Its is as if we forget who we once were, and what we are capable of creating by just allowing the imagination to run free. Let us not draw the line, but rather explore the line of child and adult.. and why we all started thinking growing up has its cost.. I think that is where we all got lost