I honestly believe my seat belt saved my life on November 1st, 2001 when my '99 Neon rolled twice while going only 40mph. It stopped on it's roof and I was hanging there in my seat, upside down, stuck there by my seat belt. Had I not been wearing it, I probably would have been thrown out of the car, like everything else in the car during the time of the wreck. The only injury I had in this accident was a small seat belt burn on my neck no bigger than a dime, bruises on my stomach from the airbag, and 2 sore fingers from where the airbag came out and pushed them backwards. This wreck could have easily killed me had I not been wearing it.
IMO, if you don't wear one, you've signed your own death certificate.
Everyone in my family automatically puts their seat belt on as soon as they get in the vehicle, and if you don't want to wear one when you ride in my vehicle then I'll politely tell you to get out and inform you that walkin' ain't crowded!