In October conference in 2006, Pres Uchtdorf said,
"The testimony of Jesus Christ and the restored gospel will help us in our lives to learn of God’s specific plan for us and then to act accordingly.
He goes on saying...
It gives us assurance of the reality, truth, and goodness of God, of the teachings and Atonement of Jesus Christ, and of the divine calling of latter-day prophets. Our testimony motivates us to live righteously, and righteous living will cause our testimony to grow stronger."