Macnair said washing your hands adds two years, and good dental hygiene can add six more years in your life. But smoking, fast food, no exercise and a stressful life can strip away 20 years. "There's no doubt younger people take life and health for granted - more than any generation before, they idle time away watching TV or playing computer games, ignoring the activities that keep them healthy or develop meaning in their lives," Courier Mail quoted Macnair, as saying.
"As we get older and start to feel the years slipping away, we suddenly realise how precious it is.
"But by then we may have already established habits (smoking, drinking, obesity, lack of exercise, stressful occupations) which take their toll and are difficult to reverse.
"Still, it's never too late to change. Also, our attitudes to older age are changing so there is more freedom now to do things later in life if we are healthy and able," she added.
A 2006 study from University of California in Los Angeles showed that men and women live healthier, wealthier, happier and longer lives when they are in a stable partnership
The study confirmed that married couples were more likely to live to an old age than their divorced, widowed or unmarried counterparts.
A stable partnership can actually add on seven years to life.
Regular exercise also adds as much as two or more years to your life.
A Harvard Alumni Study, which took into account more than 71,000 men who had graduated from Harvard University and the University of Pennsylvania between 1916 and 1954, found that those men who regularly burned 8400kJ a week while exercising lived, on average, two years longer than sedentary types.
But cigarette smoking can actually reduce 8 years from your life
Tobacco smoke contains more than 4000 chemicals, many of which are highly toxic.
A divorce can also strip away 3 years from your life, as it takes longer-lasting, emotional and physical toll on former spouses than virtually any other life stress.
Recent studies indicate that divorced adults have higher rates of emotional disturbance, accidental death and death from heart disease.
The divorced also have higher rates of admission to psychiatric facilities and make more visits to doctors than people who are married, single or widowed.