Question: What is a Spiritual Communion? How is one made?
Answer: A spiritual Communion is a mental act in which we ask our Lord to unite Himself to us in a way similar to the way He comes to us is Holy Communion. We are encouraged to make such a request of our Lord whenever we are unable to receive Sacramentally. This might be done at Mass when we are not fasting, need to go to Confession, or have already received that day; or it might be done when we are unable to get to Mass. It is clearly preferable to actually receive our Lord when this is possible, but in either case our disposition ought to be the same; a definite desire to be united with Jesus Christ.
Father Lasance suggests a formula:
O Jesus! Thou hast given us in the Holy Eucharist Thy body and blood to be our spiritual nourishment, through which we may have life everlasting. Would that I were now prepared [able] to approach the Holy Table to be united with Thee in the Blessed Sacrament! I desire, with all my heart, to receive this living Bread which came down from heaven.
O Lord, I am not worthy that Thou shouldst enter under my roof; say but the word, and my soul shall be healed. (Three times.) Let me taste, at least, the sweetness of a spiritual Communion. Come to me, Jesus, my Lord, my Master. Come and refresh my soul. Strengthen me, that in union with Thee I may do perfectly the heavenly Father's will. Let me never be separated from Thee by sin.
Keep me in Thy love and Thy grace. I will not be lured away from Thee by the deceitful honors and pleasures of the world. I love Thee above all things and with my whole heart. "Thou art the God of my heart, and the God that is my portion forever." Increase my faith, strengthen my hope, kindle my love, that I may die to self and live but for Thee.