Honestly the thought that you don't want to die or you are not ready to die. We are wired to want to live and when given the opportunity to fight to live or die most would rather live than die.
The effects of tobacco smoke on the respiratory system include:
irritation of the trachea (windpipe) and larynx (voice box)
reduced lung function and breathlessness due to swelling and narrowing of the lung airways and excess mucus in the lung passages
impairment of the lungs’ clearance system, leading to the build-up of poisonous substances, which results in lung irritation and damage
increased risk of lung infection and symptoms such as coughing and wheezing
permanent damage to the air sacs of the lungs.