"There are always two parts to true worship. There is seeing God and there is savoring God. You can't seperate these. You must see him to savor him. And if you don't savor him when you see him, you insult him. In true worship, there is always understanding with the mind and there is always feeling in the heart. Understanding must always be the foundation of feeling, or all we have is baseless emotionalism. But understanding of God that doesn't give rise to feeling for God becomes mere intellectualism and deadness. This is why the Bible continually calls us to think and consider and meditate on the one hand, and to rejoice and fear and mourn and delight and hope and be glad, on the other hand. Both are essential for worship."
-John Piper, taken from The Supremacy of God in Preaching