The Bible says, "Make a joyful shout to the LORD" (Ps. 100:1). In the Bible, shouting is associated with great achievement or joy. Joshua told Israel to march around Jericho for six days and on the seventh day to lift a great shout. When they did, the walls fell down (Josh. 6).
"Serve the LORD with gladness" (Ps. 100:2). Gladness means mirth, gaiety and happiness. No service to the Lord, whether great or small, should be done grudgingly.
"Come before His presence with singing" (Ps. 100:2). God calls us to come into His presence privately each day and together in corporate worship. "Evening and morning and at noon I will pray, and cry aloud, and He shall hear my voice" (Ps. 55:17).
The rest of Psalm 100:3 says, "Know that the LORD, He is God; It is He who has made us, and not we ourselves; We are His people and the sheep of His pasture" (emphasis added). The psalmist calls the people to recognize and "know" God's words, works and ways.
~ Robert Grant, 1779-1838