Each month, your payment consists of both interest and principal.
Your lender won't accept half payments mailed to them twice each month, but they'll likely set up a plan to deduct the payment from your bank account every other week. Most of us won't live in a single house for thirty years, but don't let that stop you from paying bi-weekly, because shorter term savings are significant. Many lenders charge a one-time fee to set up a bi-weekly payment plan.
The second figure shows how much principal remains at that same time for someone making bi-weekly payments. Your principal balance would equal the following amounts at the end of each year shown. In the following year, you'd continue to make payments of the same size. Unless you need that forced discipline, there's no reason to pay a hefty set-up fee.