Be frugal, save more, and pay more
Small sacrifices can help you save hundreds of dollars a month, cash which you can pay towards your mortgage. This could be bringing your lunch to work instead of eating out, planting a garden in your backyard to grow your own food, switching from cable TV to a streaming service, using public transport whenever you can, cancelling unused subscriptions and memberships, and choosing non-branded items over branded items.
You can also have a garage sale or a yard sale from time to time to sell off unwanted items and use the proceeds to make additional mortgage payments.