So I've tried. It comes to me especially when I am speaking the Lord's words over the chalice:
Take this, all of you, and drink from it.
This is the cup of my blood.
the blood of the new and everlasting covenant.
It will be shed for you and for all so that sins may be forgiven.
Do this in memory of me.
I think of Jesus himself, knowing he was to die so horribly the next day, and how he wanted to help his disciples understand what it meant, his death, "according to the Scriptures."
Then I think of all the martyrs who shed their blood for the truth, consecrating it into the blood of the body of Christ. And I don't just think of the martyrs we remember in the calendar, but of everyone who gives themselves for others.
Finally I think of the priests in the line of the laying on of hands that ended with me, especially Cardinal O'Malley, Pius X, Clement XIII, and Benedicts XIV and XIII.