The human heart's job is to pump nutrient-rich blood throughout your body. If you smoke, take drugs, or drink alcohol excessively, you are giving your heart extra work. How do you feel when you have too much work to do? Your heart cannot handle too much extra work over a long period of time. Over time, the health of your heart will suffer.
Scientists have proven that smoking doubles your risk of having a heart attack and doubles, triples, or quadruples your risk of sudden cardiac death. Each year, over 300,000 Americans die of smoking-related heart disease. So, don't smoke. If you do, quit. The sooner you quit, the sooner your risk will start to decline. There is hope. Former smokers can completely lower their risk of sudden cardiac death within ten years of quitting.
Because they are foreign substances, any drug can effect your heart. Even prescribed medications can. However, since prescribed medications are legal, doctors are able to control the effect a drug will have on your heart by controlling the dosage. With illegal drugs (cocaine, heroin, marijuana, amphetamines, etc.), YOU have to control the effect on your heart. Can you do that? Only if you don't take any. Even a small amount of a drug can be potentially fatal. So, don't use illegal drugs. If you do, quit.
While drinking alcohol in moderation may not pose a risk, drinking excessively does pose a serious hazard to your heart. While alcohol flows in your blood stream, the nutrient-rich blood is less able to nourish the heart. If the alcohol content is excessive, your heart will be in danger. So, don't drink alcohol excessively. If you do, quit.