Ideally, your mortgage will have been paid off by the time you retire, but there are ways to increase your immediate spending power based on the value of your home.
You may wish to buy a bigger hose, or you may want to move to nicer area.
You may wish to buy a house by the sea or even retire abroad.
With retirement villages becoming ever more popular, you may want to investigate these.
These pages offer some advice and guidance about mortgages in retirement.