A Danish study published in April of 2013 of 11,000 patients without heart disease were followed for 16 years and grouped on the basis of mental vulnerability (tendency for psychosomatic problems or poor interpersonal relationships). They found that the mentally vulnerable had a 36% higher risk for a cardiovascular event.
A second study of 14,000 people over 3 years evaluated the effects of demanding physical labor on cardiovascular risk and found that leisure activity, as expected, was beneficial, but demanding labor increased the risk for heart attacks! For those who did both kinds of exercise, the risk increased 400% compared to those with a sedentary job. Overall, those with a sedentary job had a 20% lower risk of a heart attack! There was a 60% benefit for those people with sedentary jobs who did leisure activity.
In a third article published in April of 2013, researchers found that high levels of cortisol, which reflect stress, measured in hair samples showed a higher risk for type 2 diabetes, heart attacks, stroke, and peripheral artery disease.
So, there's more to exercise than meets the eye and it is important to know more about the effects of exercise and the setting.