O God, the Eternal Father, we ask thee in the name of thy son, Jesus Christ,
First, we address Heavenly Father. Then we ask Him in humility and verify that we are doing so in Jesus's name, as we are commanded to do all things in His name (3 Nephi 27:7, 9).
to bless and sanctify this bread to the souls of all those who partake of it,
The Guide to the Scriptures on lds.org defines the words bless and sanctify as follows:
Bless: To confer divine favor upon someone. Anything contributing to true happiness, well-being, or prosperity is a blessing.
All blessings are based on eternal laws (D&C 130:20–21). Because God wants his children to find joy in life (2 Ne. 2:25), he grants blessings to them as a result of their obedience to his commandments (D&C 82:10), in answer to a prayer or priesthood ordinance (D&C 19:38; 107:65–67), or through his grace (2 Ne. 25:23) [emphasis mine].
Sanctification: The process of becoming free from sin, pure, clean, and holy through the atonement of Jesus Christ (Moses 6:59–60).that they may eat in remembrance of the body of thy Son,
As we eat the blessed and sanctified bread, our thoughts must be on the Savior's body that allows for the blessing and sanctification of our souls.
and witness unto thee, O God, the Eternal Father,
Our act of partaking the sacrament is a testimony to God and His holy court that we are going to keep the promises associated with the act.
that they are willing to take upon them the name of thy Son,
One of the definitions, and the most appropriate one, of the word willing is "cheerfully consenting or ready." Our attitude must be cheerful (Moroni 7:6-10) and we must be ready at all times to take and defend His name.
A 1978 Ensign article explains what it means to take upon His name: "We take Christ’s name upon us when we join his church; we come to be known as members of The Church of Jesus Christ of Latter-day Saints. But far more than that is involved. Because of our baptismal covenant, we have become “the children of Christ,” “spiritually begotten” by him. (Mosiah 5:7.) As our understanding of the atonement grows, we become increasingly mindful of the need “to retain … [Christ’s] name written always in [our] hearts.” (Mosiah 5:12.)"
and always remember him
An article in the December 2010 Ensign reads,
When I read this story [of the Israelites and the fiery serpents], I would say to myself, “How could the people not do something so simple when their lives depended on it?” I couldn’t understand. All that changed when the Spirit showed me how similar I was to the Israelites.
One morning, as I thought about the Savior, I recalled the sacrament prayer, which says that we may have His Spirit to be with us if we always remember Him (see D&C 20:79).
Remembering Him is more than just thinking about Him; it's also acting like Him. This New Era article has great suggestions on how to always remember Christ.It seemed so easy. Then I realized how often I get caught up in my daily life and give little thought to the Savior. I remembered that the brass serpent symbolized Jesus Christ being lifted up on the cross. Suddenly I realized that the “remember Him” in the sacrament prayer could be considered the latter-day version of looking to Him in the story of Moses and the brass serpent.
and keep his commandments which he has given them;
When we take the sacrament, we renew not only our baptismal covenants, but also all covenants we've made (Ensign, July 2012).
that they may always have his Spirit to be with them
If we do all the above--partake the sacrament worthily, take upon Christ's name, remember Christ, and keep His commandments--we will be blessed with the Spirit. "Everything the Savior’s gospel teaches us to do and become is intended to bless us with the companionship of the Holy Ghost," said Elder Bednar in General Conference October 2010.
Elder Oaks explains further:
We cannot overstate the importance of that promise. President Wilford Woodruff called the gift of the Holy Ghost the greatest gift we can receive in mortality (see The Discourses of Wilford Woodruff, ed. G. Homer Durham , 5). . . .
The gift of the Holy Ghost is so important to our faith that a prophet gave it unique emphasis in a conversation with the president of the United States. Joseph Smith had journeyed to Washington to seek help in recovering compensation for injuries and losses the Saints had suffered in the Missouri persecutions. In his meeting with the president, Joseph was asked how this Church differed from the other religions of the day. The Prophet replied that “we differed in mode of baptism, and the gift of the Holy Ghost by the laying on of hands” (History of the Church, 4:42). He later explained that this answer was given because “all other considerations were contained in the gift of the Holy Ghost” (History of the Church, 4:42).An Important Prayer
The prayer is so important that we use words divinely given us and repeat them perfectly. Sometimes it may seem frustrating to have to repeat the prayer until it is said perfectly, but it can be a blessing, as shared in this Ensign article:
In one sacrament meeting, a young priest had to repeat the sacrament prayer four times. This motivated one sister to think more deeply about the sacrament. After the meeting, she sought the young man out and said, “The first three times I wasn’t ready. But the fourth time, I was ready, and I’ve had one of the most meaningful experiences in partaking of the sacrament that I’ve had in a long time.”Challenge: Let us listen more carefully to the sacrament prayers so we know what we are asking for, promising to do, and promised to receive.