Doors. They lead to a space often hidden from view. To leave one room and to enter the next usually requires going through a door. Often, however, we want what's in the "next" room, but are unwilling to leave the "present" room. We must be willing to forfeit the familiar in order to gain the new thing.
Old ways, old thoughts and old actions won't get you to the place you want to be. If they could have, you would be there now. Try something new.