We've all heard exercise helps you live longer. But a new study goes one step further, finding that a sedentary lifestyle is worse for your health than smoking, diabetes and heart disease.

Dr. Wael Jaber, a cardiologist at the Cleveland Clinic and senior author of the study, called the results "extremely 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."