Inviting a young man to consider the priesthood is a prayerful act that should not be done lightly. If, after praying about it, you believe that someone may be called to the priesthood, pray some more – for the grace to propose it well, and that he may be open to whatever his vocation is. Pray too for the wisdom to know when and how to speak to him.
Trust your intuition and have the courage to speak to him seriously about your prayers on his behalf, and your sense that he may have a calling to the priesthood. Don’t worry too much about his response; he may respond lightly or seriously, and he may be joyful or disturbed by your words. It would be good to have a practical suggestion for him – for instance, a vocation event that he could attend or an encouragement to speak to his pastor or the Vocation Director. You might also suggest that he use the discernment resources on this website.
Once you have spoken to him, pray for him even more intensely, especially at Holy Mass, and offer prayers and sacrifices on his behalf. Beg the intercession of Our Lady that he may be generous with the Lord, as she was. Whatever his response may be, and whatever his vocation, you will have followed the Lord’s command to “pray to the Lord of the harvest to send out laborers into his harvest” (Mt 9:36-37) and perhaps planted a seed that will blossom in the future.