“Bless the LORD, O my soul…:”
Psalm 104:1 KJV
In this context, to bless God means to praise and honor Him. In simple terms, it is to tell God how great and awesome He is.
One cannot bless the Lord by being quiet, you speak, write or demonstrate. Maybe mention or list the things He did that you are really happy about.
In the sentence above, the Psalmist was telling his soul to bless the Lord.
What is the Soul? It is the seat of the will, emotion and intellect/mind of man.
Why did the Psalmist want his soul and not his body /lips or his spirit to bless the Lord?
1. God only accepts worship willingly given
2. God has emotions and He wants us to express our passion for Him even as He did us throughout the earthly ministry of Jesus Christ
3. God wants us to be fully aware and present when praising Him. Not doing it mindlessly to pass time or while being distracted.
Worshipping God grudgingly, mindlessly or without really meaning it, is abomination to God and waste of time.
So bless the Lord, O my soul!