Picture Source: Google images
"Lord Jesus, by the Precious Blood You did shed in the Garden of Olives, take pity on all aspirants to the priesthood who, through the temptations of the evil one, or dread of the responsibilities of the sacred ministry, are in danger of losing their vocation. Impart to these tortured souls sufficient courage to make the sacrifices by which the Eucharistic Chalice must be purchased; and in return for their generosity, inebriate them at the altar with the Blood which, in Heaven, shall be their eternal source of delight.
Our Lady of the Precious Blood, watch over the living chalices of the Blood of Jesus. Amen."
~from Prayers for Priests and Those Destined for the Priesthood recited daily by the Handmaids of the Precious Blood as a closing prayer after Vespers
I saw this beautiful prayer over at Anne's blog:
Imprisoned in My Bones