Miracles defy full definition, they are the manifestation of the power of God in the lives of men...Miracles are part of the gospel of Jesus Christ. They are ONE OF THE CHIEF characteristics of true believers...God is a God of miracles; everlastingly, always and without exception, he performs miracles among his people...and because he is the same yesterday, today and forever, miracles are always found among those who have faith.
(Mortal Messiah - vol 1 by Bruce R McConkie)
Doctrine and Covenants 35:8 For I am God, and mine arm is not shortened; and I will show miracles, signs, and wonders, unto all those who believe on my name.
Faith in the Lord Jesus Christ is a conviction and trust that God knows us and loves us and will hear our prayers and answer them with what is best for us.