We’ve gone through the Dave Ramsey Financial Peace University program, too.
Paying off a 4% mortgage has a guaranteed 4% rate of return.
Good for you, congrats! We paid off our mortgage long ago. Didn't see the sense of paying several times what the house is worth, in interest, so we paid extra on the principal to pay down the loan early. I've had arguments with some people that get equity cash out of their homes, ending up with high interest loans that are crazy. Told them they're crazy, but they argue that the bank gave them thousands more than they asked for. I said of course, to sink you into debt! Interest you don't have to repay, is money kept in your pocket. Unfortunately, they don't teach common sense like this in public school.