Every Roman Catholic Priest is aware of his vocation to be Eucharistic, every day of his life. Celebrating the Holy Sacrifice of the Mass should be uppermost in his mind, nothing should ever stop him from celebrating this Sacrament of God's love to humanity. From the Catechism of the Catholic Church, we all know the benefits of the Mass, for whom and why they are offered.
It is not about you, the Priest; it is about the Holy Will and Plan of God, our Creator. Like every child of God, your guardian Angel and hosts of Angels surround you, particularly being the Alter-Christus, these Spiritual Beings accompany you, everywhere. As St Pio of Pietrelcina {Padre Pio} once said: "feel free to send your guardian Angels on errands..." They are there to 'serve' us as they serve God. Personally I have often tried to do this: ask my guardian Angel to keep Jesus company after I begin my holy hour, before the Blessed Sacrament, and suddenly have need to step out of the Chapel. I simply genuflect on two knees before the Blessed Sacrament, turn and bow towards the kneeler I feel my Guardian Angel is staying and say: "please, keep the Lord company while I step out.... thank you" I have always had the feeling that I have not left Jesus - the Prisoner of Love, alone. My guardian Angel kept Him company in my brief absence.
Our awareness of this ever-presence and company of our Guardian Angels, should help keep the Priest, by God's grace, conscious of the avoidance of mortal sin.