Psalms 9:1 NKJV

“I will praise You, O Lord, with my whole heart; I will tell of all Your marvelous works.”

Praise should be like a celebration. Worship is reverent. So when David says I will praise you with my whole heart, It is proclaiming openly and possibly loudly the goodness of God and testifying openly of all His wonderful works. Good example; remember when David danced before the Lord in the open streets before the ark of the covenant? That’s a celebration!