Discernment is one of those “churchy” words that often does not have exact equivalence in the day-to-day experience of most 21st century people. But, it is an important one because one’s whole life and future depend on it. It is different from the more worldly “figuring out what I should do.”
Discernment involves trying to determine what is on the mind of God and His Church. Discernment is trying to hear the whisper of God’s calling for you in life. One does not merely decide that they want to be a priest; rather, one accepts the invitation of the Lord to be a Priest of Jesus Christ.
The saints provide us with some important ways of understanding this process. St. Ignatius of Loyola, founder of the Jesuits, has some specific advice on this. When he was laid up in bed nursing his war wounds, he trained his mind to be sensitive to his internal feelings. He read books on soldiering, but also on the lives of the saints. He noticed that both subjects held his interest and got him excited. But the feelings he had while reading the war stories left him immediately after he read them. The feelings he got from the lives of the saints intensified even after he put down the book.