Personal Worthiness

1. Personal Worthiness is necessary to accomplish missionary work.
D&C 88:74
In this verse, the Lord commanded us to be clean; and, if we try to be so, He has promised to clean us. Cleaning ones' self is achieved through our efforts and the mercy of the Lord. He will help us to gain purity and remain to be pure. However, it should be our desire to be clean. His powers are enough to wash us clean from our impurities, as long as we come to Him.
D&C 121:45
As we strive to be clean and pure before God, our love for our fellowmen will increase as well. we are to maintain this feelings by filling our thoughts of virtuous matters that will help increase our worthiness before God. Then will we gain favor in the sight of the Lord and receive His promised blessings for obeying His commandments and diligently fulfilling our duties

Called to Serve

Back in the premortal realms, us spirit children were presented choices. One of which is to follow God the Father's plan to come to earth and learn how to become like Him--and we did promise that we will return to His presence again. However, as we are sent here on earth, each spirit children are situated differently--some has closer opportunities to be in the true church than another. With this being the situation, spirit children who has chances of being in the church promised other spirit friends to find them and bring them to the light of the gospel--a promise that each of us, as members of the Church holds to the rest of our brethren here on earth.
As literal sons and daughters of our Heavenly Father, we are commanded by the Lord to teach and share the gospel with one another: ‘Behold, I sent you out to testify and warn the people, and it becometh every man who hath been warned to warn his neighbor (D&C 88:81).' We are those who share a greater light of the gospel; and in what greater way would there be for us to share the gospel than to 'embark in the service of God.'
When we enter the waters of baptism, we accepted the covenants the Lord has made with the House of Israel. Being one with the House of Israel means that we are to obey the commandments of the Lord in bringing his children back to His presence through His gospel.
This is the Lord's work--a covenant He has with with His people. It is a great blessing for us to participate in His work--"in bringing about His Covenants and His gospel unto those who are of the House of Israel (1 Ne 22: 11)"-- and great is the promise to those who accept the call to go forth and serve, for their "good name will never be forgotten in this world or in the eternities to come (Missionary Preparation Student Manual, p. 4)."