To the OP,
I suggest seeking out a group of people at Mass who you know to be faithful and joy-filled Catholics, and sitting with them. Even having one or two people next to you who you KNOW are excited about the Lord Jesus will make it better for you at Mass.
Again, I reiterate what I said in my original post–we should not look at the outside, but at the heart.
Interestingly, when my husband and I started attending the Catholic Church, we were envious of all the loving and hand-shaking and friendships that seemed to be all around us. After Mass, people would hang around and talk, and we would overhear invitations to go out to eat or come over to the game the next day, etc. So OUR impression of the Catholic Church is that it was a very loving, joyful place.
Perhaps your parish is kind of stuck in a rut. Another suggestion is that YOU start up the “Happy Train.” After Mass (in the lobby, please, or out in the parking lot if it’s warm enough), make it a point to greet several people or families. Say something like, “I’ve been going to this Mass for X years and I’ve never known your names. Could you tell me please? I’m ___ ___, BTW.”
Also, I can assure you that a smile and an enthusiastic rendition of the hymns is contagious. Many times, my husband and I have had people tell us after Mass that they love listening to us sing during Mass. So YOU do it, even if everyone else doesn’t. They will enjoy it.
One more thing–be prepared to be humbled by the Lord. I’m willing to bet CASH that if you try my “greeting strategy,” you will approach someone who looks like a dead cat throughout Mass, and you will learn, to your embarrassment, that they are filled with enthusiastic love for the Lord Jesus and His Church, that the Mass is the highlight of their week, and that they are involved in some heartrending ministry that brings joy and hope to others, and they would LOVE to get you involved in the same ministry!! How much $$ do you want to bet?!
