Metta meditation is a Buddhist practice of loving-kindness. According to the Metta Institute, "most simply, metta is the heartfelt wish for the well-being of oneself and others. When describing metta, the Buddha used the analogy of the care a mother gives her only child. Loving-kindness is closely related to the softening of the heart that allows us to feel empathy with the happiness and sorrow of the world." Remember, if you’re doing mindfulness practice, there is no such thing as a distraction. You pay attention to whatever arises in your awareness and make that an object of meditation.
Marc also wanted to share two more resources:
If you like written directions, check out this link from called "How to Do Metta"