Hi,
One who is called to the priesthood must first of all have the desire to be a priest. If the desire is not present, one is most likely not being called. There has to be an attraction—just as there is if one is being called to marriage. In both instances, one will not be adequately able to explain why one is attracted. One can point to various aspects, but a man cannot fully explain why he is so attracted to one woman that he wants to spend his life with her; so with the priesthood and religious life.
Now as necessary as the desire is, more is required. One must be able to live the life—both for marriage and for the priesthood or religious life. The final requirement is the Church’s approval. This again is true for the priesthood, religious life and marriage. I hope the helps. If you want to discuss this further, just click on my name for further private consultation. You are in my prayers.
Fr. Vincent Serpa, O.P.