We got our ~$290k 30-year mortgage in 2007. I don't remember the rate, but in the fall of 2010 we refinanced to $274k with a 20 year term at 4.25%. We always intended to pay it off early, and just to have a concrete goal we decided to pay it off in 1/2 the time. The simplest way to do that is to double up the principal portion of each payment. But I didn't like the idea of the extra payments getting larger over time, so I calculated the number that would allow us to pay the same amount every month -- a little more than $1,100. After paying that extra principal amount for seven years, our mortgage balance is now about $103k. It would have been $206k had we not made the extra payments. If we continue the extra payments, it should be paid off in just over three years. It will to be challenging to keep up the accelerated payoff while maintaining savings and continuing to fully fund 401k's and IRAs. But we're going to keep it up as long as possible. When the mortgage is gone, our yearly expenses will drop by close to $35k, which is huge for us. That will enable lots of options, including building up our taxable investments and/or switching to part time work. The best part about the last 7 years of 'forced savings' is that it forced us to live below our means. That should continue to pay dividends indefinitely, and make our goal of FIRE or ESR much easier to attain.