Lol ... that used to happen to me at the RC parish. I would sit there in judgement of others, their actions, their words, their attire. The pastor was an especially strong source of distraction. He had this silly habit of leaving words out of the Creed or singing along with the choir during certain parts of the liturgy when he was supposed to be praying silently. Since there was no crucifix in the Sanctuary, my mind fixated weekly on whether or not we had one or two acolytes. One meant they would carry the processional cross; two meant the crucifix remained in the closet and the acolytes carried candles. No crucifix in the Sanctuary during Mass, was a violation of the GIRM. It got so bad that I would simply keep my eyes closed throughout Mass.
In all honesty, however, I constantly reminded myself of all those years when I was apathetic, ignorant and indifferent towards the Mass. And they were many. It became a humbling experience to recall those years, make penance for them and seek ways to help others to avoid them. Even now I reflect on these experiences to prevent myself from becoming prideful. I have sinned and am in no position to judge others.