If you watch very closely, you’ll notice that the priest is moving his lips and praying some prayers very, very quietly during the preparation of the Gifts. The rubrics indicate that the priest should pray them ‘sub secreto’, which is translated as ‘inaudibly’ or ‘secret.’
But there’s really no secret, because the prayers are printed in the Roman Missal or other worship resources for the whole world to see. And even though the rubrics indicate that the priest is to pray these prayers, there is absolutely no reason why you can’t do that too!
As the priest pours wine and a little water into the chalice, he prays quietly: “By the mystery of this water and wine may we come to share in the divinity of Christ, who humbled himself to share in our humanity.”
Then the priest bows profoundly and says quietly: “With humble spirit and contrite heart may we be accepted by you, O Lord, and may our sacrifice in your sight this day be pleasing to you, Lord God.”
Finally, as he washes his hands he prays, “Wash me, O Lord, from my iniquity, and cleanse me from my sin.”