See your monthly payment, what paying a little extra saves you, and where every dollar goes over the life of the loan.
Principal & interest is only part of it. These start as typical estimates: swap in your real tax rate, premium, and dues if you know them.
Add to your monthly payment and see how much sooner you're done, and how much interest you skip.
Your annual payment is the same every year. What changes is how much of it builds equity vs. covers interest.