Why Mormons Send Missionaries Around The World*:
That Mormons do missionary work is one of the Church’s most recognized characteristics. Right now, tens of thousands of missionaries are walking, driving or riding their bikes around the world, handing out copies of the Book of Mormon and sharing the gospel with the people they meet. Why do these people, most of them under the age of 25, volunteer to leave their homes at their own expense and dedicate a period of their lives to preaching the gospel of Jesus Christ?
The Lord said, “proclaim my gospel from land to land, and from city to city… bear testimony in every place, unto every people” ( Doctrine and Covenants 66:5,7 ). We take that commandment to heart and look for opportunities to share the blessings we’ve received from living the gospel with everyone we can. Jesus taught, “Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God” ( John 3:5 ). Knowing that certain ordinances like baptism are necessary for us to return to live with our Heavenly Father, we feel an urgent need to share this blessing with everyone we can. Our first interest as a Church—is that as many of the children of men as can, will be saved and exalted. While we work out our own salvation, we want to help those around us do the same. Because we are all sons and daughters of our Heavenly Father, the more of us that are able to learn and keep His commandments and enjoy eternal life, the happier we’ll all be.
*Taken from mormon.org