"Now, this thing was pleasing unto me, Jacob, for I had requested it of my Father who was in heaven; for he had heard my cry and answered my prayer." Jacob 7:22
Receiving an answer to prayer is tremendously faith promoting. Anyone that recognizes an answer to prayer feels closer to God and more inclined to believe in Him. Conversely, when someone doesn't see their prayers being answered, they often conclude that either God isn't there, or, if He is, He doesn't care about them. How very important, then, to recognize the answers to our prayers.
President Thomas S. Monson recently taught:
"Reinforced constantly during my own review of the years has been my knowledge that our prayers are heard and answered. We are familiar with the truth found in 2 Nephi in the Book of Mormon: 'Men are, that they might have joy.' I testify that much of that joy comes as we recognize that we can communicate with our Heavenly Father through prayer and that those prayers will be heard and answered—perhaps not how and when we expected they would be answered, but they will be answered and by a Heavenly Father who knows and loves us perfectly and who desires our happiness. Hasn’t He promised us, 'Be thou humble; and the Lord thy God shall lead thee by the hand, and give thee answer to thy prayers'?
"...I would like to share with you just a tiny sampling of the experiences I have had wherein prayers were heard and answered and which, in retrospect, brought blessings into my life as well as the lives of others. My daily journal, kept over all these years, has helped provide some specifics which I most likely would not otherwise be able to recount." ("Consider the Blessings," October 2012 General Conference, paragraphs 4 and 5.)
I want to highlight that he mentions keeping a journal. Much of my testimony of prayer comes from writing down questions I ask in prayer and then later reviewing them and recognizing that they have been answered.