There are over 4,000 toxins in each cigarette which can't wait to get into your blood stream. It increases your blood pressure, makes your heart beat faster and damages your circulatory system. Carbon monoxide is a poisonous gas. It gets into your blood stream and replaces oxygen which you need for energy. This makes your blood stickier and puts a strain on your heart.
Smokers are often short on energy and get out of breath quickly.
Tar sticks to the windpipe and the inside of the lungs. This makes it more difficult for your lungs to work efficiently and more difficult to breathe. What's more, tar can actually damage the walls of your lungs and cause cancer. Many serious diseases are caused by smoking, including heart disease, lung cancer, bronchitis and stomach ulcers. Smoking is also bad news for people with asthma.