Actually is DOES make sense, cigarettes are HIGHLY addictive. The physical addiction is much, much stronger than your health anxiety. My father in law had lung cancer and STILL smoked. My husband tried 3 times to quit (once he lasted a year, once he tried some kind of pills that he had to stop taking because they were giving him hallucinations!)but he finally did it for good in 2009. He said that when he was younger he was hooked on various street drugs and smoking was by far the hardest to overcome. So don't beat yourself up, just keep trying, you'll do it.