To be a successful missionary one must have the Spirit of the Lord. We are also taught that the Spirit will not dwell in unclean tabernacles. Therefore, one of the first things a missionary must do to gain spirituality is to make sure his own personal life is in order.
Ezra Taft BensonI say to you with all the fervor of my soul that God intended men to be free. Rebellion against tyranny is a righteous cause. It is an enormous evil for any man to be enslaved to any system contrary to his own will. For that reason men, 200 years ago, pledged their lives, fortunes, and sacred honor. No nation which has kept the commandments of God has ever perished, but I say to you that once freedom is lost, only blood - human blood - will win it back.
Ezra Taft BensonIf we have any criticism of our leaders, we invite Satan into our lives and beliefs.
Ezra Taft BensonWhat does the Atonement have to do with missionary work? Any time we experience the blessings of the Atonement in our lives, we cannot help but have a concern for the welfare of others. ... A great indicator of one's personal conversion is the desire to share the gospel with others.
Ezra Taft Benson