As Good As It gets. Carol’s line, "What good does that ever get anybody?" (question #7)
Carol is writing a thank you note to Melvin and she starts to cry to answer to her mom' s question.
Mom: We're going out like people do. If you can't feel good about this break and step out a little...then I think you ought to have Mr Udall send you over a psychiatrist.
Carol: It's very weird now, not feeling that ...stupid panic thing inside me all the time. Without that, I just start thinking about myself. And, what good does that ever get anybody?
I don't understand the last sentence of Carol. Unfortunately the Japanese subtitle doesn't help me. I don't understand the English structure of the sentence. Which is the subject and verb? What does the subject indicate?
This sentence is as hard as the title, As Good As It Gets".
Please help me.
Thank you very much.
EDITED after Sophie's answer.
I learned this is a common phrase. Please show me some examples. What kind of situations, when, do you use the phrase?