This exercise is really Part Two of exercise # 21. Hopefully you have spent some time thinking and writing about how a stranger sees you and you've gone beyond the physical. You have written about how your posture conveys your mood (you know you walk differently when you are happy then when you are sad, etc). You have discovered that carrying a notebook and pen creates a different impression than carrying a laptop. And because I asked you to be kind, hopefully you did not write about your fat thighs (which do not exist!) but instead noted how patient you were while waiting in line behind an old woman who simply could not decide between a slice of banana bread or a blueberry muffin.
Now that you have learned all that because you hoped someone would notice it about you, go out and describe some people that you see. Go beyond their mousy brown hair, crooked teeth and glasses. Who are they? Are they having a good day? Are they shy with people, but love animals? What does the book they are carrying say about them? Try to give them the depth you hoped someone else spotted in you.