3 ideas
Zeno Cosini keeps trying to quit smoking for decades. He marks each 'last cigarette' with dated inscriptions on walls and book flyleaves, and he picks dates with numerical significance. Each resolution gives the next cigarette a special pleasure, so the vow to quit becomes part of the habit it is meant to end.
When a person narrates their own life for an authority, like an analyst, the account works as advocacy, not disclosure. The narrator admits small faults openly to earn credibility, then reframes the large failures, such as rivalry, infidelity and the father's deathbed slap, as accidents or misunderstandings. Read any self-account by asking what the confession is designed to excuse.
Zeno clings to his sense of being sick, whether through neurosis, imagined ailments or the smoking habit, because the sickness excuses his inaction and frames his failures as symptoms rather than choices. The novel ends with him rejecting his analyst's cure and declaring that life itself is a disease. On this view, 'healthy' people are simply less aware, and chasing a cure is a further delusion.