1 Ne. 2:1; Alma 17:5-11; 26:27; John 16:33; refer to the quote by Joseph F. Smith under 1 Ne. 8:2, 36
“In June 1830, Samuel Harrison Smith trudged down a country road in New York State on the first official missionary journey of the restored Church. He had been set apart by his brother, the Prophet Joseph. This first missionary traveled twenty-five miles that first day without disposing of a single copy of the new and strange book that he carried on his back. Seeking lodging for the night, faint and hungry, he was turned away, after briefly explaining his mission, with the words: ‘You liar, get out of my house. You shan’t stay one minute with your books.’ Continuing his journey, discouraged and with heavy heart, he slept that first night under an apple tree. So began, in the most inauspicious way, the missionary work of this dispensation through the restored Church, The Church of Jesus Christ of Latter-day Saints.” (Ezra Taft Benson, God, Family, Country, p. 188)
“One of the greatest secrets of missionary work is work. If a missionary works, he will get the Spirit; if he gets the Spirit, he will touch the hearts of the people, and he will be happy. Then there will be no homesickness nor worrying about families, for all time and talents and interests are centered on the work of the ministry. Work, work, work—there is no satisfactory substitute, especially in missionary work. We must not allow ourselves to become discouraged. Missionary work brings joy, optimism, and happiness. We must not give Satan an opportunity to discourage us. Here again, work is the answer. The Lord has given us a key by which we can overcome discouragement (Matt. 11:28-30).” (Ezra Taft Benson, Come Unto Christ, p. 96-97)
[To missionaries] … “you must know that Lucifer will oppose you, and be prepared for his opposition. Do not be surprised. He wants you to fail. Discouragement is one of the devil’s tools. Have courage and go forward. Recognize that the gospel has been preached with some pain and sorrow from the very beginning of time. Do not expect that your experience will be otherwise.” (James E. Faust, Ensign, May 1996, p. 42)
“I received a mission when I embraced this work; it has never been taken from me yet… . We [John Taylor and I ] have been over a great many rough roads, [and] traveled hard… . For over thirty years we have labored to preach the gospel… . In my early missions … I have waded swamps and rivers and have walked seventy miles or more without eating. In those days we counted it a blessing to go into a place where there was a Latter-day Saint. I went once 150 miles to see one; and when I got there he had apostatized, and tried to kill me. Then, after travelling seventy-two miles without food, I sat down to eat my meal with a Missouri mobocrat, and he damning and cursing me all the time.” (Wilford Woodruff, Journal of Discourse, 12:11-12)