Via Daily Dharma / Internal Enemy

Usually we define our enemy as a person, an external agent, whom we believe is causing harm to us or to someone we hold dear. But such an enemy is relative and impermanent. One moment, the person may act as an enemy; at yet another moment, he or she may become your best friend. This is a truth that we often experience in our own lives. But negative thoughts and emotions, the inner enemy, will always remain the enemy.

—Dalai Lama, "The Enemy Within"