Alma 29:11 - 29:17
Alma 29:11 Yea, and I also remember the captivity of my fathers; for I surely do know that the Lord did deliver them out of bondage, and by this did establish his church; yea, the Lord God, the God of Abraham, the God of Isaac, and the God of Jacob, did deliver them out of bondage.
In addition the mercy shown to Alma, he remembers what the Lord had done for his ancestors. He tries to keep in mind that the Lord delivered them (his father Alma and his followers as well) out of bondage which in turn paved the way to establish the church in Zerahemla.
Alma 29:12 Yea, I have always remembered the captivity of my fathers; and that same God who delivered them out of the hands of the Egyptians did deliver them out of bondage.
Along with the escaping of his father Alma, he was thinking of the escape of the children of Israel from Egypt as well.
Alma 29:13 Yea, and that same God did establish his church among them; yea, and that same God hath called me by a holy calling, to preach the word unto this people, and hath given me much success, in the which my joy is full.
The Lord did set up His church among the Nephites and called Alma to be a preacher and a leader among them. As a result of his efforts, Alma has seen many folks repent of their sins and come unto Christ which has brought him much joy.
Alma 29:14 But I do not joy in my own success alone, but my joy is more full because of the success of my brethren, who have been up to the land of Nephi.
Alma is also overjoyed with the success that his friends, the four sons of Mosiah, had among the Lamanites in the land of Nephi.
Alma 29:15 Behold, they have labored exceedingly, and have brought forth much fruit; and how great shall be their reward!
The boy work hard and as a result many were brought into the fold of God and great shall be the reward of these boys in the world to come.
Alma 29:16 Now, when I think of the success of these my brethren my soul is carried away, even to the separation of it from the body, as it were, so great is my joy.
So when Alma thinks of the great success the boys had among the Lamanites, he is so over come with joy that he almost feels like his spirit is separating itself from his body.
I have long suspected that our mortal bodies can only take so much joy before it is overloaded. I think that there is a point at which the joy that is available to the spirit is far more than the body can take. Another reason which the resurrection is so valuable to us is that it gives us a body which has the capacity to stand up to the spirit experiencing unlimited joy.
Alma 29:17 And now may God grant unto these, my brethren, that they may sit down in the kingdom of God; yea, and also all those who are the fruit of their labors that they may go no more out, but that they may praise him forever. And may God grant that it may be done according to my words, even as I have spoken. Amen.
Alma is praying that God will reward these boys the opportunity to live in heaven with God along with their converts forever. That they all will give thanks to their Father in Heaven for the mercy He showed both the boys and their Lamanite converts. This is Alma’s fondest wish and he hopes it will come to pass as he hopes.