The second letter is addressed to someone you admire. Write everything that you love and admire about them in detail, again, addressing that person directly. ("I love how adventurous you are." "You have such a gift for empathizing with people.")
Then, read the letters aloud in front of a mirror, substituting every "you" for "I". In other words, read the letters as though they are addressed to you.
Next, discuss the exercise with a friend. Having a witnessing friend present can help you see a lot more deeply into your own shadow tendencies. And you can do the same for him or her.
Now, it's crucially important to take the next step. Sit in meditation, following the breath or simply focusing your attention in the heart center. Ask that the inner Self, the power of grace, the spirit of yoga be present within you. Offer the qualities you've seen in yourself—both the dark and the light shadow qualities—to the Self. Ask, "May all imbalances be balanced. May confusion be illuminated. May the dark and light sides of myself be balanced, and may I be able to use the gifts hidden in shadow for the benefit of all beings." Once you've made the offering, sit quietly for a few minutes.
In the hours and days that follow, stay alert for any subtle inner shifts. Notice if there is a change in the way you see these other people, or in how you see yourself.