Just as the Savior adapted his prayer on the different occasions and circumstances in which he gave it, so we should always be tailoring what we pray for to our specific needs and circumstances, avoiding “vain repetitions”.
President Monson said, "If you have not read the Book of Mormon, read it." Then he made this promise that I know and have a testimony of being true.
I was a member for several years before having received a true and strong testimony of the Book of Mormon. I always knew it was true, and I had faith in it, but I never really received a true witness for years after my baptism. After having received my personal witness, I learned of the strength the Book of Mormon offers to those who live according to the words of the prophets who testify of Christ within its pages. It is a powerful source and it has greatly blessed my life.
It took me several years to realize I had the most important and effective "instruction book" at my disposal.