Offer yourself up to God’s will as Christ did. Remember, prior to spreading the Gospel, St. Peter denied Christ, St. Paul persecuted the Church, St. Augustine fooled around with women and Alphonse Ratisbonne  was an athiest who vigorously hated all things Catholic. These are just a few examples of wonderful priests who did not start out as saints, but turned their sinful lives around when they recognized God’s call.
As Pope Benedict XVI said, “To build your life on Christ, to accept the word with joy and put its teachings into practice: This, young people of the third millennium, should be your program! There is an urgent need for the emergence of a new generation of apostles anchored firmly in the word of Christ, capable of responding to the challenges of our times and prepared to spread the Gospel far and wide. It is this that the Lord asks of you, it is to this that the Church invites you, and it is this that the world — even though it may not be aware of it — expects of you! If Jesus calls you, do not be afraid to respond to him with generosity, especially when he asks you to follow him in the consecrated life or in the priesthood. Do not be afraid; trust in him and you will not be disappointed.”