Mormon talk about the need for obedience is not based in a belief in salvation by works (though sometimes some forget that it is not). It is, instead, a reminder of the obedience that our covenant requires. As this revelation says, we obey to show that we have received Christ, not in order to receive him.
The Book of Mormon gives an explanation of what it means to have the desire to be baptized. Those who have read this column more than once have probably seen me refer to my favorite LDS scripture, Mosiah 18:8-10:
[A]s ye are desirous to come into the fold of God, and to be called his people, and are willing to bear one another's burdens, that they may be light; 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, that ye may be redeemed of God, and be numbered with those of the first resurrection, that ye may have eternal life—now I say unto you, if this be the desire of your hearts, what have you against being baptized in the name of the Lord, as a witness before him that ye have entered into a covenant with him, that ye will serve him and keep his commandments, that he may pour out his Spirit more abundantly upon you?
Those who seek baptism are those who wish to be numbered among God's sheep, to be members of his household (Rom. 8:14).
Those seeking baptism are willing to bear the burdens of others. They are willing, insofar as human weakness will allow them, to imitate Jesus himself, making the lives of others easier, whether their lives are weighed down with sin, or physical ailment, or poverty, or natural disaster, or whatever.
That means mourning with mourners, rather than explaining to them why they ought not to mourn. It also means comforting, in other words strengthening, those who need comfort and strength. Those desiring baptism and membership in God's household are those willing to give mourners what they need to endure their mourning and overcome it if possible, to give sufferers what they need to endure their suffering and overcome it if possible.
Those who desire to be baptized desire to be instruments by which God fulfills the promise of the Sermon on the Mount: "Blessed are they that mourn: for they shall be comforted" (Matt. 5:4). Those unwilling to be such instruments implicitly deny their desire to be with God because they fail to imitate his character. I suspect they fail even to recognize it.
The more I've thought about my baptism forty-nine years ago and the covenant that I made with it, the more I've come to understand its depth. That increasing understanding has led me to increasing humility about my desires and abilities: I understand too well what Paul describes in Romans 7:19; I am continually more grateful for the promise that my double-mindedness can be overcome (Rom. 8:1-2).
But one need not be in his 60s to appreciate the covenant of baptism. Even an 8-year-old can understand that we must repent and trust in Jesus Christ. Even she can understand that her desire to help others makes her most like her Savior and Heavenly Father.