I have never really understood Alma 29. In it, Alma expresses the desire to be an angel and to cry repentance with a voice to shake the earth. Then, he says that he sins by wishing that. I always thought that sounded rather falsely humble. After all, is it not a great work of God to wish to cry repentance?
Now I think I begin to understand an inkling of why that was a sin. I have come to a point where I see people I love and others I care about making choices that cause them pain. It brings me a very real sorrow to see them lying to themselves and cheating themselves out of happiness, not to mention all those around them. I have felt the desire to shake them and say "Can't you see what you are doing?!" But Alma's statement that he sinned by wishing the same thing was no false humility. It was true.
Part of the price we pay for our agency is the agency of others. When it is legal to smoke, we are accepting the damage that nicotine does second-handedly to our lungs. When we choose to marry, have children or make friends we are also accepting that they have their own agency which can then hurt us by their actions. When we overcome our own natural inclinations in order to preach the gospel, we must accept that there are those who will refuse it, despite our sacrifices. When we decide to be disciples of Christ, we take upon ourselves His name and, by so doing, take upon ourselves some degree of His sorrows and travails. I wonder if the pain He felt came more from watching those He loves make choices that cause only grief. I have learned how that can be a very real pain, even if the actions of another don't affect me in any more material way. I have felt no agony more exquisite than watching someone exercise their agency in a way that causes unforeseen pain, knowing I should do nothing to restrict them from doing so.
It is a sin, perhaps one of the gravest sins, to desire to take away another's agency. All of the worst sins including murder and chastity infringements center around that desire (or at least that disregard for another's agency). Allowing others their agency in no way invalidates laws required to govern our behavior in society, but it does mean that the execution of those laws must be done with true understanding. They must not be upheld through a desire to control, only a desire to protect. It may seem like a very thin line, but I think it means a world of difference in the realms of the soul.
It is vital to remember that we have each been given an allotment from God. That allotment may include great deeds, but it more importantly and more commonly includes the small ones. It does not matter whether you serve as priesthood wielder, prophet, Nobel Peace Prize winner, sister or mother, so long as you serve as a child of God, with all the powers and divinity which come with your status. Alma was not an angel, nor was he called to be the hand by which the miraculous work of converting the Lamanites was brought about. But in his less glorious and romantic way, he was able to bring about the salvation of just as many souls. And, humbly, he was able to rejoice in the great deeds of his brethren. It may not be the tale to excite the blood of small sword-brandishing boys, but it is beautiful and glorious.