Ordination into the priesthood shifts one's relationship to the Eucharist in a lot of ways. The shifts are graced and trustworthy, but jarring at times nonetheless.
One of them, which I am thinking about today, is that you lose the option of whether or not to receive Holy Communion when you attend Mass. I didn't attend daily Mass very much before I was a religious; except for one brief period (as a student at UC Galway) daily Mass was either unavailable or precluded by my work schedule.
Since entering religious life, however, daily Mass has been more or less the norm. Not that we were ever taught this, but religious are obliged to make every effort to assist at Mass each day. (CIC 663, 2) In those seven years of my religious life before being a priest, I had a choice about whether or not to receive Holy Communion at the Mass of each day. Of course I desired to receive, and usually did, but sometimes I would not if I felt catastrophically unrecollected that day or suspected that I might be in a state of mortal sin. I don't think anyone can ever say for sure if he is in a state of mortal sin or not, but it is important for us in our examinations to not only make informed guesses, but also to err on the side of caution. A director once asked me if I occasionally declined to receive because I was worried about germs; I responded that I was more worried about my sins.
As a priest offering the Mass, you don't have the option of choosing whether or not to receive Holy Communion. It is your Communion that ratifies the Sacrifice; without it no Mass occurs. So what do I do now about those days on which I feel dangerously unrecollected or fear I might be in a state of mortal sin, not having had a chance to go to confession?
Well, first of all, the duty of offering Mass publicly imposes on me that much more of a public burden to stay recollected and avoid occasions of sins that could become mortal. But I also try to remember that I offer Mass for the sake of the people who assist, those who have offered the intention, and indeed, for the whole world. God would not hold against them any sacrilege I might occasionally commit through my own negligence and stupidity. And I trust that my effort to love and forgive those for whom I offer the Sacrifice will be God's mercy for me.