Healthy people with stressful jobs who work long hours but get little satisfaction from what they do have twice the risk of dying from heart disease as satisfied employees, according to a study. Job stress has been known to cause heart problems in people who already have cardiovascular disease  . Finnish scientists have now shown that even in healthy people the pressures of work can take their toll. High blood pressure, lack of exercise, smoking and being overweight contribute to heart disease--a leading killer in many industrialized countries. But Mika Kivimaki, of the Finnish Institute of Occupational Health, and his colleagues, who studied the medical histories of 812 healthy Finnish men and women in a metal industry company over 25 years, said job stress also plays an important role. Workers who had the highest job-related stress levels at the start of the study were more than twice as likely to die of heart disease, according to the study published in The British Medical Journal. Work stress involves too much work as well as a lack of satisfaction and feeling undervalued and unappreciated. Many people work long hours but if the effort is rewarding the stress is _  The British Heart Foundation said the results support earlier research showing that people in jobs with low control, such as manual  workers, could be as great risk of heart disease than other employees. " It is advisable for people to try to minimize levels of stress at work and for employees to allow people to have more control at work and to be rewarded for their successes," the foundation said in a statement. The author's purpose in writing the passage is to   _  .
advise people not to work long hours suggest that everyone be satisfied with everything ask us to learn to enjoy ourselves tell us that job stress threatens our health nowadays.