In Psalm 107 you have this statement repeated 4 times: “Let them give thanks to the Lord for his unfailing love and his wonderful deeds for men.”   The Psalm is introduced with the words, “Give thanks to the Lord, for he is good; his love endures forever.  Let the redeemed of the Lord say this.”

Each of these repeated statements is preceded by an explanation of the condition people found themselves in, either by their own choices or by circumstance.  In each case they got to a place where the pain or difficulty got so bad they cried out to God.  In each case when they cried out, God in mercy responded and helped them.  That’s why they were encouraged to give thanks to the Lord for his unfailing love and his wonderful deeds for men. 

The Psalmist concludes this Psalm by pointing out that God works in ways that at times don’t seem to make sense to many, but “The upright see and rejoice, (while) all the wicked shut their mouths.  Whoever is wise, let him heed these things and consider the great love of the Lord.” 

For one whose hope is in the Lord there’s a realization that God is indeed working all things together for good to those who love Him and are called according to His purpose (Romans 8:28).  Since that’s true, it’s another expression of the Lord’s unfailing love and His wonderful deeds for men.  This in turn is a further reason for giving Him thanks.