Perhaps they feel worthless. Well, be their mirror. Show them that you see their potential. Show them with your acts, words, thoughts, and feelings. Every person's life is important.
Every person has a contribution to make.
Treat each of them as special. Your support could well be the boost or turning point in someone's life, so don't let a person's outward appearance blind you to their greatness. Bring out the best in everyone by believing in them. As you adopt this attitude toward people, you will develop meaningful relationships with everyone you meet, and even a casual exchange will enrich both you and the other person. We human beings are sensitive creatures.