A lot of self-harm takes place when it comes to individual life expectancy. Smoking, eating too many calories, and being sedentary top the list in wealthier populations these days. Ignorance is also very important at the present time because of the prospects for the development of rejuvenation biotechnology: if you don't know that reversal of aging might be accomplished in future decades, then you can't make a choice to support that progress. Yet new therapies to impact aging will have a much larger effect on life span than any lifestyle choice. If they arrive in time, that is, which requires widespread public support and far greater funding than presently exists.
But people, as a general rule, don't tend to put a great deal of value on the distant years of their own personal future. We know this because there are so many who smoke, get fat, and don't exercise, and who choose to remain fairly ignorant of the workings of their own body vis a vis long-term maintenance.
Despite recent declines in the numbers of people smoking and tar yields of cigarettes, smoking remains the leading preventable cause of death in Europe. Previous studies had demonstrated that prolonged cigarette smoking from early adult life was associated with about 10 years loss of life expectancy, with about one quarter of smokers killed by their habit before the age of 70. Stopping at ages 60, 50, 40 or 30 years gained back about 3, 6, 9 or the full 10 years. However, the hazards of continuing to smoke and the benefits of stopping in older people had not been widely studied.In the current study, scientists tracked the health of 7,000 older men (mean age 77 years, range 66 to 97) from 1997 to 2012 who took part in the Whitehall study of London civil servants. Hazard ratios (HRs) for overall mortality and various causes of death in relation to smoking habits were calculated after adjustment for age, last known employment grade and previous diagnoses of vascular disease or cancer. During the 15-year study 5,000 of the 7,000 men died. Deaths in current smokers were about 50% higher than in never smokers, due chiefly to vascular disease, cancer and respiratory disease. Deaths in former smokers were 15% higher than in never smokers, due chiefly to cancer and respiratory disease.
Smokers who survive to 70 still lose an average of 4 years of life. Average life expectancy from age 70 was about 18 years in men who had never regularly smoked, 16 years for men who gave up smoking before age 70 but only about 14 years in men still smoking at age 70. Two-thirds of never smokers (65%), but only half of current smokers (48%), survived from age 70 to age 85.