A prayer that we can pray to unite our hearts to the Holy Sacrifice of the Mass:
"Heavenly Father, I unite my heart to the altar wherever Mass is being celebrated at this moment. Please make of my own heart an altar so that I can offer myself to You there, in union with Jesus's self-offering on the Cross. As Jesus offers His Body and Blood to You, let me offer myself along to You with Him. Amen."
Every day we can make a Act of Spiritual Communion so that we receive the grace that we would receive if we were able to receive Holy Communion:
My Jesus,
I believe that You
are present in the Most Holy Sacrament.
I love You above all things,
and I desire to receive You into my soul.
Since I cannot at this moment
receive You sacramentally,
come at least spiritually into my heart. I embrace You as if You were already there and unite myself wholly to You. Never permit me to be separated from You.
Amen.