Arrange one more Civic, and do the following:
Drive the car at around 40 km/h, and bang it in to a wall, while wearing your seat belt, and check for the damage on your body.
Now drive the other Civic you arranged for this activity around the same speed, and bang this one also into the wall, this time without wearing seat belt, evaluate the damage once again on your body.
P.S. Always bang while wearing seat belt first, otherwise you might not be able to bang it again if you try without seat belt first.
Disclaimer: This suggestion WILL NOT help you disable the seat belt warning, BUT it will disable the thought of disabling it in your mind, by disabling you.
Disclaimer 2: This post is not meant to offend anyone. Always wear your seat belt while driving, and if possible your helmet also (as Storm would put it).