Researchers found that 60 per cent of all deaths in Ontario can be blamed on those five unhealthy habits.
They say smoking, physical inactivity and poor diet each shaves off about two years off life expectancy.
They also say that overall, Ontarians would gain more than seven years of life expectancy if everyone were in the healthiest category for all five behavioural risks examined.
The study also found that nearly all Ontarians have at least one of the five risk factors for shortening their lives, and the researchers say improving healthy behaviour will not only lengthen life, but also the amount of healthy life.
The study involved researchers from the Institute for Clinical Evaluative Sciences, Public Health Ontario, the Ottawa Hospital Research Institute and the University of Ottawa.
"Individually, if we all make one change like smoking less or being more physically active, then collectively we would be significantly healthier and live much longer," said study author Doug Manuel.
"The impact that modifiable behaviours have on our health is astounding. Not only will we increase our life expectancy but being healthier will mean there will be fewer demands on both formal care giving like hospitals and informal care like family," said Manuel in a statement.