Dear God our Father, today we remember the supper which your only Son left to his Church to show us his love. He gave it to us when he was about to die, and commanded us to celebrate it as the new and eternal Sacrifice, which we do with gratitude at least every Sunday. This year we are unable to do this. But at this moment I come before Jesus in sorrow for any sins I have committed, and, although I cannot be at Mass and receive Holy Communion, I trust you will come spiritually into my heart. Dear Jesus I believe you are truly with me. I thank you for showing me such love. Help me to show you love now in my life. Amen

Information about Spiritual Communion can be found on the Wikipedia page https://en.wikipedia.org/wiki/Spiritual_Communion

an abstract from the page is copied below :

According to the official Catholic handbook (enchiridion) for indulgences, “an Act of Spiritual Communion, according to any pious formula, is enriched with a partial indulgence.”

It also specifically mentions this Act of Spiritual Communion, which was recommended by St. Alphonsus Liguori:

My Jesus, I believe that Thou art present in the Blessed Sacrament. I love Thee above all things and I desire Thee in my soul. Since I cannot now receive Thee sacramentally, come at least spiritually into my heart. As though Thou wert already there, I embrace Thee and unite myself wholly to Thee; permit not that I should ever be separated from Thee. Amen.

Cardinal Rafael Merry del Val composed this Spiritual Communion:

At Thy feet, O my Jesus, I prostrate myself and I offer Thee repentance of my contrite heart, which is humbled in its nothingness and in Thy holy presence. I adore Thee in the Sacrament of Thy love, the ineffable Eucharist. I desire to receive Thee into the poor dwelling that my heart offers Thee. While waiting for the happiness of sacramental communion, I wish to possess Thee in spirit. Come to me, O my Jesus, since I, for my part, am coming to Thee! May Thy love embrace my whole being in life and in death. I believe in Thee, I hope in Thee, I love Thee. Amen.

Another example is:

As I cannot this day enjoy the happiness of assisting at the holy Mysteries, O my God! I transport myself in spirit at the foot of Thine altar; I unite with the Church, which by the hands of the priest, offers Thee Thine adorable Son in the Holy Sacrifice; I offer myself with Him, by Him, and in His Name. I adore, I praise, and thank Thee, imploring Thy mercy, invoking Thine assistance, and presenting Thee the homage I owe Thee as my Creator, the love due to Thee as my Savior. Apply to my soul, I beseech Thee, O merciful Jesus, Thine infinite merits; apply them also to those for whom I particularly wish to pray. I desire to communicate spiritually, that Thy Blood may purify, Thy Flesh strengthen, and Thy Spirit sanctify me. May I never forget that Thou, my divine Redeemer, hast died for me; may I die to all that is not Thee, that hereafter I may live eternally with Thee. Amen.

Piarist fathers have taught this short act of Spiritual Communion, popularized by St. Josemaria Escriva:

I wish, Lord, to receive you with the purity, humility and devotion with which your most holy Mother received you, with the spirit and fervour of the saints