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.
God has a calling on each man’s life. Furthermore, He enables men to fulfill their appointed work. Man, however, must be strong and DO the work.
Change often results in fear. As such, it must be met with strength. Failure to do so can breed panic that only God's strength can overcome.
