One way to recover some of the lost self esteem in extreme depression

During depression, a person often evaluates him/her self to be worth less and incompetent , fundamentally incompetent and incapable. In extreme examples like mine, I often used to wonder the reason for my continued existence ,and even doubt that my coming into this world was of any use. No wonder, this is followed by suicidal tendencies; the person thinks it would be better if he were gone , or even wish he wasn't born in the first place. To quote a famous poet,
" O had I perished in the womb,
that deed were left undone"
This kind of pathological thinking requires urgent professional attention. However, there is one way we can feel better in such a situation, temporarily atleast.
We can help other people . Of course this isn't easy , considering the fact that the individual doubts his ability to help himself. One way this can be done easily without much effort is to pledging to donate our eyes after our death. This will provide the person some evidence he isn't entirely useless, and regardless of whatever he has been unable to achieve , he will continue to be useful to the world even after he is gone.
I did this, and I have also volunteered to donate my blood to help other needy people. This assures me that no one on this planet is essentially useless, and that we all have capability to be useful and contribute something to this world.
We all feel better after having helped somebody, and in depression such acts often help recover some segment of the person's initial self respect and self esteem.