There is nothing like seeing the growth of the Church to get you excited about missionary work. The film "An Ensign to the Nations" does just this. It shares several different examples of missionary success stories, and the Lord preparing people and nations to receive the gospel. It shows the gospel being preached by missionaries, by members, and by those not yet members. She shows the growth of the church in every continent.
The movie concludes with a stirring rendition of "A Marvelous Work is about to Begin." This includes showing many different temples, and also different groups singing the song including missionaries, young people, at the Hawaii Temple and at the Argentine Temple. The movie is very effective and sets the tone for wanting to do more. It was produced in 1997, and since this time the church has seen considerable growth.
It was made for TV by the church in 1997, and is very inspiring.