The world is a big place and over 7 billion people are continuously polluting it. But every once in a while, for everyone, this world just shrinks down –in one person. Then that person becomes the whole world to you. Her acceptance, her denial, her every opinion is the beginning and the end of any argument. Fear of losing that person makes you weaker than the weakest you have ever been and you are the strongest knowing that person is standing beside you. Sharing a fun moment becomes your biggest joy and all the ups and downs of the life seem like a adventure ride of a theme park. Although, it is not good for your salvation, it is the only way you would prefer to lead your entire life. The smile can do wonders, even the tears. You are ready to change yourself. You are ready to do things which you have never done before. You are ready to stretch yourself beyond your limits. The anchor can help you pass the strongest of storms and without it you are a ship without a sail.
In short, that person can bring the best and the worst out of you. Suppose you have that kind of power over someone what you would do :)