The step-by-step process that leads to heart attack is not fully understood. Major risk factors, though, are well-known, and some can be controlled. Of these, the main ones are high blood pressure, high cholesterol, obesity, smoking, diabetes and a sedentary lifestyle. Stress may also raise the risk, and exertion and excitement can act as triggers for an attack. Another important risk factor is family history. A family history of heart disease can increase the risk in both men and women at earlier ages.