In the Catholic Church, the month of June is dedicated to the Sacred Heart of Jesus. This great feast in the Church is always celebrated on the octave day of Corpus Christi, the feast which celebrates the Body and Blood of Christ. The feast of the Sacred Heart falls nineteen days after Pentecost Sunday. The following day is the feast of the Immaculate Heart of Mary, so these two devotions to the hearts of Jesus and Mary are side-by-side on the liturgical calendar.
Devotion to Jesus' Sacred Heart is perhaps the most popular in the Church today, and it had its beginning in 17th century France. In 1672, Christ appeared to a French Visitation nun, St. Margaret Mary Alacoque. Over a series of visits, Our Lord revealed to St. Margaret Mary the importance of devotion to His Sacred Heart. He asked that His heart, wounded on the cross and continually wounded by ingratitude of men for his sacrifice for them, be venerated and adored as an embodiment of His Divine mercy and love.
Jesus especially asked that all people go to Confession and receive Holy Communion often, especially on the First Friday of each month, and that reparation be made for sins committed against His Sacred Heart and the Holy Eucharist. He also requested that the Church observe a feast day specifically for the purpose of this reparation. In 1856, the Solemnity of the Sacred Heart was officially added to the liturgical calendar.
You can have a devotion to the Sacred Heart by doing as Our Lord asked, by receiving Holy Communion frequently (especially on the first Friday of each month), monthly confession, veneration of an image of His Sacred Heart, and prayers and sacrifices offered out of love for Him and for the conversion of sinners.
Jesus also gave us, through St. Margaret Mary, special promises for those who keep a loving devotion to the attribute of His infinite love for mankind as represented in His Most Sacred Heart.
12 Promises of the Sacred Heart of Jesus
1. I will give them all the graces necessary in their state of
life.
2. I will establish peace in their homes.
3. I will comfort them in all their afflictions.
4. I will be their secure refuge during life, and above all, in
death.
5. I will bestow abundant blessings upon all their
undertakings.
6. Sinners will find in my Heart the source and infinite ocean
of mercy.
7. Lukewarm souls shall become fervent.
8. Fervent souls shall quickly mount to high perfection.
9. I will bless every place in which an image of my Heart is
exposed and honored.
10. I will give to priests the gift of touching the most
hardened hearts.
11. Those who shall promote this devotion shall have their
names written in my Heart.
12. I promise you in the excessive mercy of my Heart that
my all-powerful love will grant to all those who receive
Holy Communion on the First Fridays in nine
consecutive months the grace of final perseverance; they
shall not die in my disgrace, nor without receiving their
sacraments. My divine Heart shall be their safe refuge in
this last moment.