Alma 31:31

O Lord, my heart is exceedingly sorrowful; wilt thou comfort my soul in Christ. O Lord, wilt thou grant unto me that I may have strength, that I may suffer with patience these afflictions which shall come upon me, because of the iniquity of this people.

Our souls are comforted in Christ when we are comforted by the love of Christ, which is given to us through the power of the Holy Ghost, who is the Comforter. We are comforted about the troubles we face by the knowledge that Christ has suffered all things and overcome all things. He will not let us fail if we are trying. He will make up for our weaknesses and pardon our mistakes. We can have hope and comfort in this life and the rest of the Lord in the life to come.

Alma 13:12

Now they, after being sanctified by the Holy Ghost, having their garments made white, being pure and spotless before God, could not look upon sin save it were with abhorrence; and there were many, exceedingly great many, who were made pure and entered into the rest of the Lord their God.

To be made pure is to be redeemed, and to enter into the rest of the Lord is to have one's calling and election made sure. That exceedingly many have had this experience gives us hope. It is not impossible, and it is not rare.

Alma 12:34

Therefore, whosoever repenteth, and hardeneth not his heart, he shall have claim on mercy through mine Only Begotten Son, unto a remission of his sins; and these shall enter into my rest.

According to D&C 84:24 the "rest of the Lord" is the fullness of his glory. In other words, exaltation in the celestial kingdom. Thus we have the formula for exaltation: repent, harden not our hearts, and claim Christ's mercy through the Atonement. We keep our hearts from hardening when we keep trying to keep the commandments even though we fail constantly. When we give up and decide we are too weak and imperfect to even bother to try, that is when we harden our hearts. As long as we recognize our guilt and are not satisfied with our efforts, we are still salvageable. We have to keep our eye fixed on the mercy of Christ.