HELP me figure this quote out please ~! Thanks !?

What does ,"Remember Cedric. Remember, if the time should come when you have to make a choice between what is right and what is easy, remember what happened to a boy who was good, and kind, and brave, because he strayed across the path of Lord Voldemort. Remember Cedric Diggory. " said by dumbledore in HP and the goblet of fire means ? I dont understand this quote .. PLEASE HELP !