Smoking is the single most preventable cause of death in many countries. That is right, death. Smoking kills hundreds of thousand of people every year. The life expectancy of someone who smokes is reduced by about 15 to 25 years. The chances of developing life-threatening illnesses such as lung and other cancers, heart attacks, strokes and emphysema are increased. Even if these ailments do not kill you then they are likely to greatly reduce your quality of life.