The Psalms are a collection of ancient songs, reflecting Israel's experience with God. In Psalm 9, David opens his song like this (vs.1-2):
I will praise the Lord with all my heart;
I will tell of all the marvelous things you have done.
I will be filled with joy because of you.
I will sing prises to your name, O Most High.
Note the order here:
1. Thankfulness. David took time to think of all the good things God had done. This cultivated a grateful attitude and outlook on life. He was focusing his mind on the positive, not everything that might have been going wrong.
2. Praise. As a result, David's mouth declared God’s works. He spoke out his praise.
3. Joy. As a result, David was filled with joy because of God. Gratefulness always results in joyfulness.
4. Singing. David's heart then erupted into song.
What good things has God done recently for you? Take time to reflect on them, praise him for them and allow his joy and song to fill your heart and life. What a difference that makes to the atmosphere of our world.