If rather than paying your mortgage monthly, you started making your payments on an accelerated bi-weekly or weekly basis, you will reduce the number of years it takes to pay off the mortgage.  

Accelerated weekly and accelerated bi-weekly payment options are calculated by taking a monthly payment schedule and assuming only four weeks in a month. We calculate an accelerated weekly payment, for example, by taking your normal monthly payment and dividing it by four. Since you pay 52 weekly payments, by the end of a year you have paid the equivalent of one extra monthly payment. This additional amount accelerates your mortgage payoff by going directly against your loan's principal. The effect can save you thousands in interest and take years off of your mortgage.