Prepay the interest with points. Helps to start with a mortgage broker that sells below market to begin with.
For example, I showed up at closing with an extra $20k and prepaid the interest on the loan, to the extent that they allowed, which left me with next to no interest owed, hence the low rate. This doesn’t work if your flipping houses, since you have to be in the home for XX months to break even on that interest, but after a couple years you’re way ahead because you’ve saved hundreds per month on interest payments. You could have moved that to principal payments or just enjoyed a lower mortgage payment. I have zero incentive to pay more than my monthly dues on the mortgage because I’m basically not paying interest. The bank got their $20k up front for signing the deal and forfeited their long term play of $100-200k in interest over the life of the loan. They still have the house if I stop paying (as with any other mortgage). Also, because it was an interest payment, I was able to claim it on my taxes and get half of it back the first year. Anyway, it took a bit of work to make it happen, there was no falling into this deal, took months of work.