"Be the change you wish to see in the world."

In order to "Be the change you wish to see in the world." you would have to be the first person to lead by example. Weather its a positive or negative change, you have to be the one to make that effort to change yourself in the way you want this world to be. "Be the change..." implies that you want to change yourself as a person in anyway possible in order to do or become something or someone. "...you wish..." is self explanatory, you want something to happen that you think you want. "...to see in the world." means that you notice things that you might be happy with or disagree with. Therefore "Be the change you wish to see in the world." means that you want to change yourself in the way that you want the world you are unsatisfied with to be.