Heaviness in the heart of man maketh it stoop: but a good word maketh it glad. Proverbs 12:25 KJV https://bible.com/bible/1/pro.12.25.KJV
The song, Don’t worry, be happy! Is a good representation of this principal from God’s Word. During stressful times it is hard to feel happy and joyful, but by keeping your your focus on the blessings that are yours through Jesus Christ you can feel joyful. Because of the eternal life that is yours because of His sacrifice.