Praying Backwards: Transform Your Prayer Life by Beginning in Jesus' Name by Bryan Chapell is temporarily available for the Amazon Kindle for free! As usual, even if you don't currently have an Amazon Kindle, you can still download it to your computer or Android or Apple tablet and use Amazon's Kindle software to read it.
Though I have not had an opportunity to read the book, I can't share higher praise than Tim Challies who said this about the book:
Praying Backwards was an answer to prayer. The subtitle to this book is "Transform Your Prayer Life By Beginning In Jesus' Name." I truly feel that Chapell's teaching, drawn directly from the Scriptures, will transform the prayer lives of many of God's people, and for that I am most thankful. I simply cannot recommend this book enough.I must admit, it makes me want to set aside the time to read it. Get it while it's [UPDATE: $6.99].