I believe the key to successful missionary work is to be sincere and genuine. A question we must ask ourselves often is, "do I look at missionary work as only an obligation, or do I focus on the opportunity?" The obligation side of missionary work was a result in becoming a member of the Church. The scriptures validate this in Mosiah 18: 8-10
and now, as ye are desirous to come into the fold of God, and to be called his people, and are willing to bear one another’s burdens, that they may be light;
9 Yea, and are willing to mourn with those that mourn; yea, and comfort those that stand in need of comfort, and to stand as witnesses of God at all times and in all things, and in all places that ye may be in, even until death, that ye may be redeemed of God, and be numbered with those of the first resurrection, that ye may have eternal life—
10 Now I say unto you, if this be the desire of your hearts, what have you against being baptized in the name of the Lord, as a witness before him that ye have entered into a covenant with him, that ye will serve him and keep his commandments, that he may pour out his Spirit more abundantly upon you?
Now that we have established ALL members of the church have the obligation to be a missionary lets separate the whole hearted missionaries from the task driven missionaries. The whole hearted missionary sees missionary work as an opportunity to help others come to Christ. (Mosiah 28: 2-3) Whole hearted missionaries are sincere, they desire the welfare of all souls because the love Christ, and their fellow men. Whole hearted missionaries don't find missionary work a burden, rather their joy comes from helping others discover their divine potential. Whole hearted missionaries emulate Christ. They have "felt to sing the song of redeeming love," and desire others the same blessing. Christ isn't just spoken by whole hearted missionaries, but is seen in the countenance of the individual. Do we see the pattern here? Christ-like love separates a whole hearted missionary from the rest. Successful missionaries serve because they love Christ. They've taken the obligation they've made at baptism and earnestly seek out opportunities to serve others.