D&C 13

As John the Baptist confers the Aaronic priesthood upon Joseph Smith and Oliver Cowdery, he makes three doctrinal points concerning this priesthood authority, that it  -

"...holds the keys of the ministering of angels, and of the gospel of repentance, and of baptism by immersion for the remission of sins..."  (Doctrine and Covenants | Section 13:1)

In a later revelation we learn -

"The priest's duty is to preach, teach, expound, exhort, and baptize, and administer the sacrament,
47 And visit the house of each member, and exhort them to pray vocally and in secret and attend to all family duties." (Doctrine and Covenants | Section 20:46 - 47)

And -

"The teacher's duty is to watch over the church always, and be with and strengthen them;
54 And see that there is no iniquity in the church, neither hardness with each other, neither lying, backbiting, nor evil speaking;
55 And see that the church meet together often, and also see that all the members do their duty."  (Doctrine and Covenants | Section 20:53 - 55)

"And is to be assisted always, in all his duties in the church, by the deacons, if occasion requires."  (Doctrine and Covenants | Section 20:57)

The point I want to make is that in this duty, teaching and work, worthy Aaronic priesthood holders are entitled to the influence of "ministering angels" to those that serve.

Elder Dallin H. Oaks taught -

“The scriptures recite numerous instances appeared where an angel personally. Angelic appearances to Zacharias and Mary (see Luke 1) and to King Benjamin and Nephi, the grandson of Helaman (see Mosiah 3:2; 3 Ne. 7:17–18) are only a few examples. When I was young, I thought such personal appearances were the only meaning of the ministering of angels. As a young holder of the Aaronic Priesthood, I did not think I would see an angel, and I wondered what such appearances had to do with the Aaronic Priesthood.

“But the ministering of angels can also be unseen. Angelic messages can be delivered by a voice or merely by thoughts or feelings communicated to the mind. President John Taylor described ‘the action of the angels, or messengers of God, upon our minds, so that the heart can conceive . . . revelations from the eternal world’ (Gospel Kingdom, sel. G. Homer Durham [1987], 31).

“Nephi described three manifestations of the ministering of angels when he reminded his rebellious brothers that (1) they had ‘seen an angel,’ (2) they had ‘heard his voice from time to time,’ and (3) also that an angel had ‘spoken unto [them] in a still small voice’ though they were ‘past feeling’ and ‘could not feel his words’ (1 Ne. 17:45). The scriptures contain many other statements that angels are sent to teach the gospel and bring men to Christ (see Heb. 1:14; Alma 39:19; Moro. 7:25, 29, 31–32; D&C 20:35). Most angelic communications are felt or heard rather than seen.

“How does the Aaronic Priesthood hold the key to the ministering of angels? The answer is the same as for the Spirit of the Lord.

“In general, the blessings of spiritual companionship and communication are only available to those who are clean. As explained earlier, through the Aaronic Priesthood ordinances of baptism and the sacrament, we are cleansed of our sins and promised that if we keep our covenants we will always have His Spirit to be with us. I believe that promise not only refers to the Holy Ghost but also to the ministering of angels, for ‘angels speak by the power of the Holy Ghost; wherefore, they speak the words of Christ’ (2 Ne. 32:3). So it is that those who hold the Aaronic Priesthood open the door for all Church members who worthily partake of the sacrament to enjoy the companionship of the Spirit of the Lord and the ministering of angels.” (Dallin H. Oaks, “The Aaronic Priesthood and the Sacrament,” Ensign, Nov. 1998, 39.)