That which is of God is light

D&C 50:24

That which is of God is light; 

and he that receiveth light, and continueth in God, 

Receiveth more light;

And that light growth brighter and brighter

Until the perfect day.

Section 50 of the Doctrine and Covenants is so good for us missionaries to read.  It applies directly to us.  Verses 13 &14 say:

Wherefore, I The Lord ask you this question--

Unto what were you ordained?

to preach my gospel by the Spirit,

Even the comforter which was sent forth to teach the gospel.

Verses 26 &27 

He that is ordained of God and sent forth,

The same is appointed to be the greatest, notwithstanding he is the least

And the servant of all.

Wherefore, he is the possessor of all things;

For