St. Leonard of Port-Maurice offers this advice for receiving Spiritual Communion: In order to facilitate a practice of such great excellence, ponder what I have to say. When the priest is about to give himself Communion in Holy Mass, do you, keeping composed externally and internally, excite in your heart an act of true contrition, and humbly striking your breast, in token that you acknowledge yourself unworthy of so great a grace, make all those acts of love, of self-surrender, of humility, and the rest, which you are accustomed to make when you communicate sacramentally, and then desire with a lively longing to receive your good Jesus, veiled in the sacrament for your benefit. And to kindle your devotion, imagine that most Holy Mary, or some saint, your holy advocate, is holding forth to you the sacred particle; figure yourself receiving it, and then, embracing Jesus in your heart, reply to Him, over and over again, with interior words prompted by love: “Come, Jesus, my Beloved, come within this my poor heart; come and satiate my desires; come and sanctify my soul; come, most sweet Jesus, come!” This said, be still; contemplate your good God within you, and, as if you really had communicated, adore Him, thank Him, and perform all those interior acts to which you are accustomed after Sacramental Communion.

Here is a formal prayer to pray while following St. Leonard’s advice, though you can pray in your own words, if you prefer: