Stay positive friend. As a full member of the millions of people who feel worthless I find that staying positive and having a good attitude about things is very helpful. Get out of the house every once and a awhile. Do your good deed for the day by talking to random people, make a donation, or help people out. If you do these sort of things than in the eyes of the people you are a good and kind person. At that point you would be no longer worthless feeling. And you would physically be worth something to people.