Psalm 41:4 I said, Lord, be merciful unto me: heal my soul: for I have sinned against thee
David prays for mercy and healing. He feels in a bad way and knows he needs help. He admits that it is his own sin that has diseased his soul, and he believes God for mercy and grace to heal him and make him whole. He knows that he cannot help himself, but he knows God can.
We also experience hardship and troubles in life, but what we don’t always know is that my soul is broken because “I have sinned.” So we confess our sins, repent of them, and believe Jesus for forgiveness and healing. We could blame others or blame God. We could look to other sources for help. We could try to heal ourself. But no, we look for, and trust in, God to be merciful and to heal our diseased soul. Thank God, through Christ He does.