Up to 20,000 people are dying from heart problems every year as a result of excess alcohol, so-called "couch potato" lifestyles and poor diets, experts have warned.
Public Health England (PHE) has urged people to check their "heart age" and undergo tests that forecast when an individual might suffer a heart attack or stroke.
The Heart Age Test asks over-30s to answer a series of questions about their lifestyle and physical health.
If the tool estimates that an individual's "heart age" is higher than their actual age, they will be told they have an increased chance of having a heart attack or stroke and advised how to cut this risk.
The test has been completed more than 1.9 million times, PHE said, with four out of five people recording a heart age higher than their actual age.
Health officials urged the public to make lifestyle changes, in order to cut the risk of heart disease.
Take the Heart Age Test here:
Around 24,000 deaths a year from the condition occur in those under 75 and four in five cases are preventable - equivalent to around 50 deaths daily.
Prof Jamie Waterall, national lead for cardiovascular disease at PHE, said: "Millions are at risk of cardiovascular disease but don't know it, putting themselves at real risk of suffering ill health or dying younger.
"Knowing your heart age is a simple way of finding out whether you're at risk of a heart attack or stroke. By making important lifestyle changes you can reduce your risk before it's too late."
Cardiovascular disease is the leading cause of death among men and the second in women.
People can improve their heart health by losing weight, quitting smoking, exercising regularly and cutting back on alcohol.
Simon Gillespie, chief executive of the British Heart Foundation, said: "Millions of people in the UK are unknowingly living at high risk of a heart attack or stroke due to their lifestyle, their family history of heart disease, or undiagnosed conditions including high blood pressure and cholesterol.
"Our message today is that it's never too late to change.
"Take the test, and if you are concerned by the age of your heart, make an appointment to see your GP."