D&C 4

As he desired to know the will of the Lord concerning him, the Lord said to Joseph Smith, Sr., the father of the Prophet -

..."if ye have desires to serve God ye are called to the work..." (Doctrine and Covenants Section 4:3)

Does that mean that anyone that wants to serve may serve the Lord how he chooses or any self appointed office. Of course not. I believe that the Lord is saying that first, if ye desire to serve you are not limited in sharing your testimony and assisting and serving others. To be baptized we must be -

"...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..." (Book of Mormon Mosiah 18:8 - 9)

With baptisms we are called to this work. At that time, Elder George Albert Smith said -

"My understanding is that the most important mission that I have in this life is: first, to keep the commandments of God, as they have been taught to me; and next, to teach them to my Father's children who do not understand them. . . . It is not necessary for you to be called to go into the mission field in order to proclaim the truth. Begin on the man who lives next door by inspiring confidence in him, by inspiring love in him for you because of your righteousness, and your missionary work has already begun. [Sec. 4:4-7, quoted.]" (George Albert Smith, CR, October 1916, pp. 50-51.)

But to preach and testify with authority to the world as an authorized representative, the Lord has added -

"That as many as shall come before my servants Sidney Rigdon and Joseph Smith, Jun., embracing this calling and commandment, shall be ordained and sent forth to preach the everlasting gospel among the nations—" (Doctrine and Covenants Section 36:5)

And -

"...those who desire in their hearts, in meekness, to warn sinners to repentance, let them be ordained unto this power." (Doctrine and Covenants Section 63:57)

For in this service in going forth to preach to the world -

"...you need not suppose that you are called to preach until you are called." (Doctrine and Covenants Section 11:15)

But nonetheless, if we have a desire to serve, we should approach our leaders with this desire. It never seems to fail that if we are qualified, in consequence we are called to the work.