Some are carrying babies, or leading little children by the hand. They wait in line, patiently, but surrounded by distractions. The choir is singing, or perhaps the congregation. They receive, they turn, they must find their way back to where they were sitting or standing. Perhaps they have to climb over or squeeze by others to get to their place.
Concentration is so very difficult under the best of circumstances.
Do what you are doing. Don't be thinking of what you were doing, will be doing, might be doing, should be doing. Don't think of the people around you, the sounds, the sights, the heat. We are receiving the Lord of heaven and earth. We are leaping into his very being.