Most of people are uncertain of their lives because they do not know what will happen tomorrow, but this is not applied to believers in God. It is only God the Creator who knows what will happen in the future and who controls everything in the universe and death and life, fortune and misfortune of human beings. When King Jehoshaphat was attacked by the allied army of the Gentiles, he did not rely on the wisdom and strength of men but appointed those who sang to God and those who praised Him in holy attire and let them go out before the army. When he depended on God alone this way, he and his people completely defeated the enemy. If we fully rely on God, we can prepare our lives against uncertain future.
"Man's steps are ordained by the Lord, how then can man understand his way?" (Proverbs 20:24)