Where does our suffering unite with Christ's?

https://traffic.libsyn.com/anunslife/RNC-AS162-Oct-10-2014-OP-Columbus-June-Mattie-unite-suffering-christ.mp3
Podcast Recorded:

A listener wonders what it means to "unite our suffering with Christ's," but is afraid to ask her pastor. The Nuns discuss!

in silhouette, person bows over a small cross