I have felt that EXACT same way. It leads me to feeling horrendously guilty about being alive and not contributing.

I have no answers, I just want to let you know you are not alone. Also, I wanted to tell you, the time when I felt the most like your above quote...i was in the throws of a profound depression. I ended up leaving my job, taking a deep breath, getting a new job (that helps people). Leaving the old job was one of the best decisions I have ever made... I don't regret it for a second. For the record, the "new job" i got after quitting, paid less and I didn't care because it felt like i got parolled from the old job! Plus, every day I get to help people. I feel like helping others has helped me like myself more.

Show yourself some love. You are worth something. Who can you help today, right now, to help yourself feel better? Help one person or creature a day and it will move you toward recovering your self-worth.