So, how do Catholics "offer up" their sufferings and sacrifices? In both formal and informal ways.
Formally, many Catholics make the [Morning Offering ](http://www.fisheaters.com/morningoffering.html)to give to Our Lord that day's efforts, works, joys, sufferings, intentions, etc. (the form may vary). At the Mass, we excercise our lay priesthood by consciously, silently, privately offering ourselves up, along with the Son, to the Father during the Offertory.
Informally, we "offer it up" by simply asking God in our own words to use a suffering as it occurs; we often do this for specific intentions (ex., "Use this pain, Lord, for the salvation of my brother..."). We might follow the example of the young St. Thérèse of Lisieux and make use of [Sacrifice Beads](http://www.fisheaters.com/sacrificebeads.html), or the extraordinary among us might make the [Heroic Act of Charity](http://www.fisheaters.com/prayingforthedead.html#heroic) for the souls in Purgatory.
It's quite a discipline to react to suffering this way! In mental or physical pain? Drop something on your toe? Putting up with a co-worker who is making your life a living Hell? Enduring the constant ache of arthritis? Standing in line at the grocery and hating every minute of it? Spill the milk? Accept these things in peace, and ask God to use them for the good of the Church or for a more specific intention close to your heart. This isn't easy to do (and I in no way claim to be good at it), but it *does* make the suffering more meaningful and less -- well, less insufferable!