Jesus said to the crowds: "I am the living bread that came down from heaven; whoever eats this bread will live forever; and the bread that I will give is my flesh for the life of the world." John 6:51
Is this so hard to believe? The Jews quarreled among themselves, wondering how this could be.
We could take it the wrong way, as some do and sacrifice flesh and blood in order to eat of flesh and drink of blood, like those who sacrifice to the darkness.
It is going through Jesus that we will have life. It is eating of the Bread he chose to give us as a way for us to eat of his flesh, as is the wine, fruit of the vine that he chose to gives us to drink in imitation of his Blood.
In this way he unites us with Himself, to create with us all who partake, the Body and Blood of Christ. We become Him, we serve each other in imitation of Him.
Since we are the Body and Blood, it should not be hard for us to believe then that the Eucharist is the very life of Christ, where he lives and dwells, day and night. When the bread becomes consecrated, we now know the truth of Jesus being ever present in this very special act of love he lovingly gave us. What a very special gift he has given for all of us to become one with Him.