D&C 12

To the saints, the Lord has declared -

"...whosoever will thrust in his sickle and reap, the same is called of God." (Doctrine and Covenants Section 12:4)

The emphasis is "will" or is willing. Again, to thrust in his sickle and reap is two fold, to -

"...keep my commandments, and seek to bring forth and establish the cause of Zion." (Doctrine and Covenants Section 12:6)

And then the Lord explains what is required of the "willing" to establish the cause of Zion -

"....I speak unto you, and also to all those who have desires to bring forth and establish this work;
8 And no one can assist in this work except he shall be humble and full of love, having faith, hope, and charity, being temperate in all things, whatsoever shall be entrusted to his care." (Doctrine and Covenants Section 12:7 - 8)

And if one is willing and "humble and full of love, having faith, hope, and charity, being temperate in all things, whatsoever shall be entrusted to his care", then willing to -

"...give heed with your might, and then you are called..." (Doctrine and Covenants Section 12:9)