It has nothing to do with how you feel, it is a safety concern. The biggest concern with driving is whether your sternum has healed enough to hold up if you are in an accident. As a driver you sit far closer to the airbag, since on the driver side it is in the steering wheel and in the dash on the passenger side. If the airbag were to hit an unhealed sternum the results could be disasterous. No one plans to be in an accident, we cannot control everything that happens on the road. Best to wait until you have the go ahead that the sternum is solid and sit as a passenger with the seat as far back as it will go. Sorry to be so graphic, but the ER nurse in me says, don't take the chance.