Sticking with four of the five habits could cut your risk of dementia and cognitive decline by 60 percent, as well as reduce your risks of diabetes, heart disease, and stroke by 70 percent.
Lead author Professor Peter Elwood, from Cardiff University's School of Medicine in the UK, said switching to a healthy lifestyle had a "far more beneficial effect than any medical treatment or preventive procedure."
"The size of reduction in the instance of disease owing to these simple healthy steps has really amazed us and is of enormous importance in an ageing population," he said.
"What the research shows is that following a healthy lifestyle confers surprisingly large benefits to health -- healthy behaviours have a far more beneficial effect than any medical treatment or preventive procedure."
The study involved data from 2,235 men in South Wales over a 35-year period.
Findings were published on December 9 online in the journal Plos One.