D&C 15

 With much of the recounts of Joseph Smith's experiences, obviously, John Whitmer was kind of wondering what was in it for himself, to which the Lord told him - 

"...many times you have desired of me to know that which would be of the most worth unto you.

5 Behold, blessed are you for this thing, and for speaking my words which I have given you according to my commandments.

6 And now, behold, I say unto you, that the thing which will be of the most worth unto you will be to declare repentance unto this people, that you may bring souls unto me, that you may rest with them in the kingdom of my Father."  (Doctrine and Covenants 15:4–6)

It always seems that those things that are of greatest worth is related to our relationship with others.