It’s common knowledge that there are many benefits to being fit, but one large new study found that skipping out on the gym is particularly bad for your health.

In fact, the study claims not exercising may be more harmful to your health than smoking.

New findings, published Friday in the journal JAMA Network Open, detail how researchers at the Cleveland Clinic studied 122,007 patients from 1991 to 2014, putting them under treadmill testing and later recording mortality rates. Researchers found a clear connection between a longer, healthier life and high levels of exercise. The report calls for health care professionals to encourage patients to achieve and maintain a robust fitness routine.

“Cardiorespiratory fitness is inversely associated with long-term mortality with no observed upper limit of benefit,” the study says. “Extremely high aerobic fitness was associated with the greatest survival and was associated with benefit in older patients and those with hypertension.”

Although it is widely understood that an active lifestyle can lead to a healthy life, the study concludes that a sedentary lifestyle is the equivalent of having a major disease and the simplest cure is exercise.

Dr Wael Jaber, co-author of the study, called the results surprising.

“Being unfit on a treadmill or in an exercise stress test has a worse prognosis, as far as death, than being hypertensive, being diabetic or being a current smoker,” Jaber told CNN. “We’ve never seen something as pronounced as this and as objective as this.”

The study also took a look at the risk of being overactive and found that “ultra” exercisers do not face higher risk of death: the research consistently found that the more a person exercises the lower their mortality rates.

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Write to Gina Martinez at gina.martinez@time.com.