To ward off the risk of stroke, there’s a simple new mantra: Put down the smartphone and get up off the couch.

Adults who spend eight or more hours a day of leisure time watching television or using computers or phones face a much greater threat of strokes and cardiovascular disease. That’s the main finding by University of Calgary researchers, who followed more than 140,000 people for nearly a decade.

If using electronic devices and being sedentary eight hours a day seems like a lot, consider this: The American Heart Association says U.S. adults spend an average of 10-and-a-half hours a day watching television or using electronic devices. Adults ages 50 to 64 spend the most time connected to media.

The researchers determined a particularly hazardous nexus of inactivity and leisure time. For those under age 60 who were the least active and reported eight or more hours of leisure time, the risk of stroke was seven times greater than people who had half as much free time.

Even being only marginally active has its drawbacks, the researchers noted. Eight or more hours of free time and low physical activity more than quadrupled the risk of stroke.

The findings are not just a cautionary tale for those who are late middle age or older. Despite a general decline in overall stroke rates, the American Heart Association says the incidence has increased more than 40% in younger adults over the past several decades.

Here’s how to increase your odds of cardiovascular health: Aim for at least two-and-a-half hours of moderate-intensity activity per week.

When it comes to stroke risk, couch surfing may be the riskiest activity of all.