In several places, scripture has said that this passion comes from praying with full devotion to our Father in Heaven. The passage when Jesus visited the ancient Americans first came to my mind, "he came unto his disciples, and behold, they did still continue, without ceasing, to pray unto him; and they did not multiply many words, for it was given unto them what they should pray, and they were filled with desire." (emphasis added 3 Nephi 19:24)
I searched for pray filled. I learned that Solomon prayed and the house of the Lord filled with His glory. Peter and John were filled with the Holy Ghost. Prayer can fill us with "knowledge of his will in all wisdom and spiritual understanding".
The more humble part of the Nephites "did fast and pray oft, and did wax stronger and stronger in their humility, and firmer and firmer in the faith of Christ, unto the filling their souls with joy and consolation, yea, even to the purifying and the sanctification of their hearts, which sanctification cometh because of their yielding their hearts unto God."
Unspeakable joy filled the souls of those who heard Jesus praying for them in ancient America. When we pray with all the energy of our hearts, we are filled with the pure love of Christ
Other faiths refer to the Atonement of Jesus as the Passion of Christ. I think it is this same passion that filled the subjects of king Benjamin,
And they all cried with one voice, saying: Yea, we believe all the words which thou hast spoken unto us; and also, we know of their surety and truth, because of the Spirit of the Lord Omnipotent, which has wrought a mighty change in us, or in our hearts, that we have no more disposition to do evil, but to do good continually.A passion of obedience to the Lord's will.