In recent years, I've begun using Psalm 136
as a prayer of thanksgiving- especially during Thanksgiving season. While the phrase "His love endures forever" (or something similar) repeats at the end of each verse, this is a psalm of thanksgiving. It reminds us of His unceasing and unfailing love. Through trial and triumph He is with us. This psalm gives us a model in which we can pray. Here's what I mean...
Read through the psalm. Psalm 136 tells of God's love through Himself, His creation, Old Testament times, and personally, today. Now, as you finish reading verse 26, continue.
You might ask, "What do you mean? The psalm ends with verse 26."
State something you're thankful for. For example, "I'm thankful for God who gave me faith through Jesus Christ." Next, follow up that simple, personal, statement with, "His love endures forever" (or the wording used in your Bible). Next, state something else you're thankful for. It can be a truth about God's character, a promise stated in Scripture, something God has given you or provided, or anything else you're thankful for- whether in this moment or in the past!
I've witnessed this psalm come to life, and more importantly, people I've prayed this psalm with filled with joy as they prayed.