First ask yourself why you want to pay the mortgage off first. Paying off your mortgage simply means sending in more than is due and there are many ways to do that. But make sure that is the best strategy for you. Let's take a look at what I mean by that.
If you have other debt such as credit cards, auto loans, personal loans, almost any other debt that you are paying interest on, you need to question your desire to pay off the mortgage before those debts. Your mortgage is a simple interest debt that is often the largest tax deduction you have. Also, paying extra money against your mortgage does not lower your payment, and if you need access to money in an emergency you can only get that money back by refinancing, if you can qualify in today's difficult market.
If you ever get in financial trouble, you're better off to have cash on hand or access to credit you've paid down than to have sent in your extra cash against your mortgage.
Paying down your mortgage does build your equity, but many people have lost their home in a financial crisis despite the fact that they had paid their mortgage down. In fact, if the bank has to consider foreclosure on 2 homes they are going to be more likely to sell the one with the most equity since they stand to take less of a loss, or even make money.
You also need to have a financial planner or professional look at your retirement picture before deciding to pay down your mortgage. Your extra money may be needed to prop up your retirement account rather than going against your mortgage.
My point is, unless you have no other debt and you know for sure your retirement fund is where it needs to be, seek a professional opinion before putting your extra money against the mortgage.