Dexter is correct. My feelings have often echoed yours Starry. We have to remember that we are indeed fighting a valiant battle against depression. We need to try to do away with the judgements of self worth, failure, and wasting our lives.
For we are certainly not wasting our lives. We are worthy and each day is a success. As for volunteering, I agree that is is helpful. I do so at the local library and it has helped during times of lack of motivation and feelings of loneliness and isolation.
As for what you can volunteer with...well I would maybe jot down some things you enjoy to do in your free time and look at your town's website/local paper and see what things they offer...often times you'll find a rec center or what not that offers tons of opportunities that you may be interested in. I hope this helps you and you are having a good day.