I have several co-workers and friends that do not think it is important to wear their seatbelt. Their excuses are usually "it's uncomfortable" or "I'd rather not be trapped in an accident." My parents made a huge deal out of wearing seatbelts all the time, regardless of front/back seat. When I was first learning to drive, the rule was (when I was driving my friends) that I couldn't put the car in gear until everyone was buckled in. If they didn't want to, then they couldn't ride with me. I still follow that philosophy now, even though I get grief from friends/co-workers.
I just saw a new "Buckle Up" commercial that gave the following stats:
if you have a wreck at 20 mph, without your seatbelt it is like falling from a 2-story building
if you have a wreck at 40 mph, without your seatbelt it is like falling from a 6-story building
if you have a wreck at 60 mph, without your seatbelt it is like falling from a 12-story building
Crazy. So, please, BUCKLE UP!!