A lifetime of habit of having a smoke any time anger or fear or frustration or hurt. I remember my mom offering me a smoke after a trauma at the age of fifteen. I did not know she knew I had started. We tried to hide it as a kid but our parents were not as dumb as we thought. I watched my sister talk back to mom once and when mom butted her smoke my sister did run. I watched my other sister start smoking two packs a day after her husband left her. She was so stressed that she wanted a smoke while she was having a smoke. If anxiety is the feeling when the nicotine drops and the brain needs the nicotine quicker when stress happens, it creates a loop. The payoff is short lived. That few seconds of relief that a puff used to give. I am still working on better ways to react to stress. Thankfully there are many better ways.