You often can't really change how you feel about life. You may consider yourself fat even though your husband says you look so sexy, or you may feel under-appreciated at work even though objectively you are doing just fine. What you can try to do though, you can try to compensate in your actions the way you perceive things. So even if you view yourself as a mouse, you can nevertheless roar like a lion whenever life demands it. You do that because a higher authority tells you that is who you truly are.
You can disregard the voice in your head or the feelings you experience in order to reach the reality that truly reflects your Self. Say you are greedy but you don't act on it because your consciousness tells you to. Say your mind says, "get that promotion at any cost", yet your conscience tells you not to take advantage of others. Or say your body begs, "conquer that attractive woman", yet your heart tells you not to cheat on your soul-mate.
Caroline Knapp describes in Appetites the yin version of deviating from the Self. If greed is the yang energy that wants to conquer, indulge and take over, anorexia is the exact opposite. It is the desire to shrink physically; the need to punish the body for some psychological reason. The problem statement is one of perception, anorexic people perceive their body different from reality. They see fat where there objectively is none. Caroline Knapp eventually healed herself from this disease by forcing herself to eat against her will. The question is, can you in fact reprogram your way of seeing when you look into the mirror?
Affirmations are the conscious attempt to bring the self closer to the Self. The way to heal greed is to acknowledge that what you have is in fact awesome. Sheryl Crow puts it well in Soak Up the Sun, "It is not about having what you want, it's wanting what you have got." You can learn to discover that. Just open your eyes, life will teach you to see the world with new eyes. Step outside of your head and fall in love with life and you will experience reality quiet differently. You will discover a stunningly attractive woman where you saw only fat thighs in your mirror before. You suddenly meet a well-meaning friend or a colleague who is struggling colleague where you perceived a ruthless competitor only yesterday.
Spirituality is the art of engaging and falling in love with what is. The voice in your head or some unpleasant sensations may still exist but they increasingly fall short in the new reality that you perceive. Use affirmations to override your interferences, understand where cravings, desires or fears come from, but most importantly, just show up every day and let this world teach you who you truly are and what really is going on. Discover yourSelf in the mirror as well as the real world.