In 2002, St. John Paul II designated the Feast of the Sacred Heart as the World Day of Prayer for the Sanctification of Priests.
Why? Because the priest is Alter Christus (Another Christ). His heart must be conformed to the Sacred Heart. But priests are human. They get tired, lonely, and tempted. The devil attacks them harder because "if you strike the shepherd, the sheep scatter" (Zechariah 13:7).
How to Pray for Your Priest
1. Offer a Holy Hour
Go to Adoration specifically for him. Pray that he falls in love with the Eucharist daily.
2. Fast for Him
Pick a day (Friday is good) to fast from a meal or a comfort, offering the suffering for his purity and strength.
3. A Prayer for Priests (by St. Thérèse of Lisieux)
O Jesus, I pray for your faithful and fervent priests; for your unfaithful and tepid priests; for your priests laboring at home or abroad in distant mission fields; for your tempted priests; for your lonely and desolate priests; for your young priests; for your dying priests; for the souls of your priests in Purgatory. But above all, I recommend to you the priests dearest to me: the priest who baptized me; the priests who absolved me from my sins...
4. Say "Thank You"
Send a card. Tell him a specific homily that helped you. Priests hear complaints all day; be the encouragement.
Without the priest, there is no Eucharist. Without the Eucharist, there is no Church. Pray for them. Find prayers for clergy on MyPrayerTower.