At one point in the Bible we find King David thanking God for all He has given them in order to build a temple. After David praises God, he asks that God will help the people always remember the things they are seeing—the abundance of luxurious materials that have been given them to build the temple. As King David says, "Keep this for ever in the imagination of the thoughts of the heart of thy people, and prepare their heart unto thee" (1 Chronicles 29:18).
Alma in the Book of Mormon urges the people of Zarahemla to do a similar thing. He says, "Now behold, I say unto you, my brethren, you that belong to this church, have you sufficiently retained in remembrance the captivity of your fathers? Yea, and have you sufficiently retained in remembrance his mercy and long-suffering towards them? And moreover, have ye sufficiently retained in remembrance that he has delivered their souls from hell?" (Alma 5:6). Both King David and Alma recognize the power our thoughts have on us. Thoughts determine all action and behavior. If we are continually savoring good thoughts, our actions will naturally be good.
David and Alma want their people to choose to fill their minds with thoughts of gratitude and wonder and praise because they know the power of good thoughts. They know that the power isn't just in having positive thoughts. The power comes from centering our thoughts on God and His goodness—on what He has done and will do and is doing for us. The more we remember Him, the more we use our imagination to think about him, the more faith and hope and joy come into our lives. What we think about is a choice. The faith, hope, and joy are a consequence of that choice.
There is power in allowing our minds to consciously review all that is good.