Following is the section on Eucharistic Adoration from the Directory on Popular Piety and the Liturgy on the Vatican Website
164. Adoration of the Blessed Sacrament is a form of Eucharistic cult which is particularly widespread in the Church and earnestly recommended to her Pastors and faithful. Its initial form derives from Holy Thursday and the altar of repose, following the celebration of the Coena Domini [Lord’s Supper] Mass. This adoration is a most apt way of expressing the connection between the celebration of the memorial of the Lord’s Sacrifice and His continued presence in the Sacrament of the Altar. The reservation of the Sacred Species, so as to be able to administer Viaticum to the sick at any time, encouraged the practice among the faithful of recollection before the tabernacle and to worship Christ present in the Sacrament (175).
Indeed, this worship of adoration has a “sound and firm foundation”  especially since faith in the Lord’s real presence has as its natural consequence the outward and public manifestation of that belief. Therefore, the devotion prompting the faithful to visit the Blessed Sacrament draws them into an ever deeper share in the Paschal mystery and leads them to respond gratefully to the gift of Him who through His humanity constantly pours divine life into the members of His Body.  Abiding with Christ the Lord, they enjoy His intimate friendship and pour out their hearts before Him for themselves and for those dear to them and they pray for the peace and salvation of the world. Offering their entire lives with Christ to the Father in the Holy Spirit, they derive from this sublime colloquy an increase of faith, hope, and charity. Thus they foster those right dispositions that enable them with due devotion to celebrate the memorial of the Lord and receive frequently the bread given us by the Father. (176)
165. In adoration of the Blessed Sacrament, which can take different forms, several elements deriving from the Liturgy and from popular piety come together and it is not always easy to determine their limits (177):
- a simple visit to the Blessed Sacrament: a brief encounter with Christ inspired by faith in the real presence and characterized by silent prayer;
- adoration of the Blessed Sacrament exposed for a period of time in a monstrance or pyx in accordance with liturgical norm (178);
- perpetual adoration or the Quarantore, involving an entire religious community, or Eucharistic association, or parish, which is usually an occasion for various expressions of Eucharistic piety (179).
The faithful should be encouraged to read the Scriptures during these periods of adoration, since they afford an unrivaled source of prayer. Suitable hymns and canticles based on those of the Liturgy of the Hours and the liturgical seasons could also be encouraged, as well as periods of silent prayer and reflection. Gradually, the faithful should be encouraged not to do other devotional exercises during exposition of the Blessed Sacrament (180). Given the close relationship between Christ and Our Lady, the Rosary can always be of assistance in giving prayer a Christological orientation, since it contains meditation of the Incarnation and the Redemption (181).
(109) Sacrosanctum Concilium, 102.
(175) Cf. Pius XII, Encyclical letter Mediator Dei in AAS 39 (1947) 568-572; Paul VI, Encyclical letter Mysterium fidei in AAS 57 (1965) 769-772; Sacred Congregation of Rites, Instruction Eucharisticum mysterium, nn. 49-50, in AAS 59 (1967) 566-567; Rituale Romanum, De sacra communione et de cultu mycteria eucharistici extra Missam, cit., 5.
(176) Sacred Congregation of Rites, Instruction Eucharisticum mysterium, nn. 49-50.
(177) On the matter of indulgences attached to Eucharistic adoration and processions, cf. Enchiridion indulgentiarum, Aliae concessiones, 7, pp. 54-55.
(178) Cf. Rituale Romanum, De sacra communione et de cultu mycteria eucharistici extra Missam, cit., 82-90; CIC, canon 941.
(179) Cf. CIC, canon 942.
(180) Cf. Reply ad dubium on n. 62 of the Instruction Eucharisticum mysterium, in Notitiae 34 (1998) 133-134; concerning the Rosary, see the following note.
(181) Cf. Paul VI, Apostolic Exhortation Marialis cultus, 46; Letter of the Congregation for Divine Worship and the Discipline pf the Sacraments (15.1.1997), in Notitiae 34 (1998) 506-510; see also the rescript of the Apostolic Penitentiary of March 8, 1996, in Notitiae 34 (1998) 511.
(taken from “Directory on Popular Piety and the Liturgy ¬ Principles and Guidelines”. Copyright © 2002 Adoremus: Society for the Renewal of the Sacred Liturgy. All rights reserved. http://www.adoremus.org/0902EucharisticAdoration.html)