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“The wind blows where it pleases; you can hear its sound,
but you cannot tell where it comes from or where it is going.  
So it is with everyone who is born of the Spirit” (John 3:8, NJB).

 
As we are not always prepared for or able to receive the Eucharist, it is helpful to make an ‘act of spiritual communion’ by prayerfully asking for the graces of the Blessed Sacrament whenever we are not able to physically receive it.  For the Spirit moves as it pleases and God can grant tremendous blessings whenever and wherever.  (Such prayer is advantageous for those who are not Roman Catholic and do not receive Communion at Mass.  One may always ask God to provide the very same graces spiritually.  This devotional act is well worth trying and is a beautiful way to participate at Mass.)  In this way, we can spiritually commune with God hundreds of times a day if we like.  Here are two common versions of this prayer; however, one may compose one’s own version as needed.  You may even want to structure your own post-Communion prayer based on these humble sentiments of love and trustful surrender.
 

O Jesus, I turn toward the holy tabernacle where You live hidden for love of me.  I love You, O my God.  I cannot receive You in Holy Communion.  Come nevertheless and visit me with Your grace.  Come spiritually into my heart.  Purify it.  Sanctify it.  Render it like unto Your own.  Amen.  – Sacred Congregation of Indulgences

My Jesus, I believe that You are in the Blessed Sacrament.  I love You above all things, and I long for you in my soul.  Since I cannot now receive You sacramentally, come at least spiritually into my heart.  As though You have already come, I embrace You and unite myself entirely to You; never permit me to be separated from You.  Amen.
– St. Alphonsus de Ligouri

For more information, go to Our Catholic Prayers – devotional information,
including a summary of spiritual communion:
ourcatholicprayers.com/spiritual-communion