How do I go about coping with the thought of not being good enough when all I do is be there for others e enough if they don't deserve me

I been dealing with this for a long time and it gets me so depressed when I try to be there for someone I start to shut down and give up I know I'm a good person but it seems like the world doesn't want me at times when all I try to do is help those in need even though I'm struggling myself