I want a greater understanding of suffering in our human experience.

I have heard Brooke talk about avoiding unnecessary suffering. I know that suffering and struggle can be refining and a teaching experience in our lives and so therefore it can have a purpose in helping us to become. Physical pain can cause us to suffer. But, do you think all mental and emotional suffering is unnecessary? Just trying to wrap my head about it. My sister, who struggles and suffers a lot mentally and emotionally embraces her suffering as vital in her learning and personal growth. Thoughts?