zvei dinim,
Reuven decides to smoke one cigarette a year. He does not plan or expect to smoke a second cigarette that year. He is full control of his faculties and not dependent on anyone else’s choices. On what grounds can you say it is assur for him to smoke his cigarette?
This is not a case where he is subject to someone else’s bechira (which he can’t control). He is in full control, and he is not expecting to be unable to resist the temptation (in contrast to someone who knows that under torture he will serve A”Z, chas v’shalom).