Yes, if you can manage it comfortably every month, do pay it off. 500 a month off capital for a decent length of time could make a huge dent in your mortgage term and interest. Make sure that before you start sending in your cheques monthly that you have it in writing from your bank that the money will be taken directly off the capital as otherwise they may try to apply it to the interest instead.
There is one alternative also, you could always save the 500 a month in a savings account that earns higher interest than the rate you pay on your mortgage. Make it a savings account where you have to give plenty of notice, which will help you avoid the temptation to dip into it! Do you know what your current interest rate and outstanding balance is? You could continue to save this until mortgage interest rates start to increase (hopefully never as I say!) and then pay it off in one large lump sum, again directly to the capital. But, either option is up to yourself, so do as you feel comfortable with. Best of luck with it.