"Some people tell a story about you that you like, and you like them in return. We call these people 'friends.'
Others tell a story about you that you don't like, and you don't like them either. These are our 'enemies.'
In both cases, you have defined yourself based on the opinions of others. Your ego is strengthened and your sense of personal importance is affirmed by outside, ephemeral sources. This is a dangerous way to live.
For instance, when someone loves you, you use his or her story to tell yourself that you are worthy of love. When you meet someone who doesn't like you, you agree with that, too, and judge yourself accordingly.
Although one of the Four Agreements is 'Don't take anything personally,' without awareness, you take everything personally. Everyone has been guilty of this at some point. You assume that others' actions are somehow motivated with you in mind, when in reality you have no way of knowing the other person's intentions or circumstances. By defining who you are in someone else's terms, you give away your power to define yourself.
Without awareness, everything that happens is personal. We often think the advice 'Don't take anything personally' applies to negative ideas only. This is certainly where it starts, but remember that we shouldn't take positive ideas personally, either. You are beautiful and perfect, regardless of whether anyone else tells you so. Truth does not need confirmation from anyone."
-excerpt from Living a Life of Awareness: Daily Meditations on the Toltec Path by Don Miguel Ruíz, Jr.