The most crucial step you can take to lower your risk of heart disease is to quit smoking. Smoking is one of the leading risk factors for coronary heart disease, heart attack, and stroke. Smoking causes a buildup of a fatty substance (plaque) in the arteries, which eventually leads to a hardening of the arteries (atherosclerosis). Smoking damages organs and worsens many other risk factors for heart disease. It reduces your amount of good cholesterol (HDL) and raises blood pressure, which can cause increased stress on your arteries.