OK, So I went back to What Does the Prayer Really Say and Fr. Z's latest post is on today's Gospel reading, where Jesus encounters the demoniacs of Gerasene. Go read the whole thing, but I have to post this snippet here:
Let us not forget that even though Christ is risen and victorious, this world still has its prince. This is the enemy of our soul.
The malice of the fallen angels is so great that they will overcome the agony they experience in the present of the sacred, just for the opportunity to trip us. Enduring the terror of the Presence of the Blessed Sacrament itself, they will attack you at Mass. They will defy the sacraments and sacramentals just for a chance to bring you down a notch, if not entirely.
Be always wary of the enemy. Do not forget that demonic possession and oppression are REAL phenomena. When you are at Holy Mass, remain always aware of the glory of the sacred mysteries and that you, because of your saving baptism, can be a true and active participant.