Everytime we drive anywhere for the last 23 years, we wear them. Hardly ever before that.
When my wife was very pregnant with our (now 23 year-old) son, we got t-boned on the driver's side by some guy in a Chevy P/U who had lost control of his truck in the rain. We got hit hard enough to spin us right off the road.
Both of us were knocked around a bit, but mostly unhurt. The other guy was fine. The paramedics showed up in minutes. Neither one of us had been wearing our seatbelts and that was the first question they asked us. My wife opened her mouth to give them the "seatbelt isn't comfortable and it goes across my stomach...yada, yada, yada..." speech. She gets out "Uh", but the paramedic is already talking and he really tears her a new one. He's giving her the "it is safer" lecture and then launches right into "you are responsible for other lives now". He reloads and then blasts me with the both barrels for being the negligent father and letting my wife drive around with our baby unprotected. Because of her advanced pregnancy they transported her past other hospitals right to the downtown hospital because that's where the Neonatology ward was located.
They left me standing in the road, in the soaking rain watching the ambulance drive off with my wife and unborn child.
Surprisingly the car (although later totalled by the insurance company) still ran and after prying on the fender with the tire iron, I drove it home. As it turned out, we (all 3 of us) were fine, just a little sore the next day.
We bought a new car and promised each other to always wear our seatbelts after that.
Now it feels weird to drive across the parking lot unbelted.