Catholics believe that Jesus is truly and substantially present in the Eucharist, and when they approach the altar to receive the bread and wine, they do so to receive Jesus himself.
At times this belief can be difficult to comprehend and remains a mystery of the Catholic Church. This is why it is important to regularly affirm our faith in Jesus' Real Presence, especially before receiving him in Holy Communion.
Here is a prayer from the early 20th century that can be said before receiving communion to assert your faith that Jesus is truly there under the appearances of bread and wine.