The right kind of sorrow is often needful and brings with it certain benefits. Yet, it is in the joy of the LORD that God's people specifically find strength.
Solomon's mother advised him not to give his strength unto women. He ignored this advice and his wives turned away his heart after other gods.
The Lord is the strength of His people. While it is true that we are called to do our part, God must add the necessary strength to accomplish the work.
God knows everything, but this does not eliminate man’s responsibility to confess his sins. Failure to do so forfeits God’s practical forgiveness.
Some believers err on the side of laziness while other believers err on the side of taking no rest. Both can be life threatening in one’s walk with God.