Catholic Ragemonkey

What say you?
I would like to hear some ideas and feedback to assist me as a Pastor dealing with a pastoral challenge. Regardless of state in life, I'm sure many of you have some gems to share. Perhaps our married readers -- here is an enormous and slow pitch to the guys at Sirach 40:20 (knock it out of the park, boys!) -- could particularly share their thoughts in response to this post.

As a priest I encounter Catholics who, for whatever reasons, have married outside of the Church. I wonder how to best instruct and catechize such folk about understanding the real and experienced difference between a civil marriage versus a marriage lived as a Sacrament. Please understand these rather narrow parameters and respond to these parameters in the comment box and not other issues. IN PARTICULAR, what sort of instruction and explanation would you give to couples who have been married outside of the church for a number of years, say a decade or more, and who finally get around to having the marriage "blessed" in the Church? How do we best explain how their marriage will be different after the blessing as compared to before? Notice, in my mind, the question seems particularly apt for couples married for a number of years outside of the Church versus couples married only briefly before they seek to regularize the marriage in the Church. Let me hear your responses.