Change your observations; change your attitude.
Change your attitude; change your life.
Attitude is the combination of beliefs and feelings that effect how you view the world and how you react to it.
Beliefs are closely held values accepted as facts and validated by repeat observations.
Therefore, if you change what you look for (observations), you will change your beliefs. If you change your beliefs, you will change your attitude. If you change your attitude, you will change how you react to the world (and therefore how it reacts to you).