Hi Bru - I did this - starting about 10 years ago. I used a payments calculator to work out what my payments should be to pay off the house before I retire. It was about double My last payment is March, I retire in June with no debt. I am SO glad I made that decision and paid the darn thing off!
Start by reducing you extra expenses that are not necessary, I changed my phone plan to a lower one, got rid of a cable and for rid of my gym membership and stated to work out at home. I also pack my lucky daily and got rid of all but one credit card.
An extra mortgage payment each year-you can direct it towards the principal or the interest. Google "Clark Collins", a financial genius from the HLN channel-the man has MOUNDS of info & on one of his shows, this was a suggestion he made.