I just read a sermon entitled "The Expulsive Power of a New Affection" by Thomas Chalmers. You can read it here. I highly recommend printing that out, taking about an hour to read it (for meditation and because the English is old), and then hopefully you will be exhorted, encouraged, and amazed as I was after reading it.
To go with the sermon, I made this graphic from a quote near the end:
Feel free to download and share. (Click the image first and then save it.)