When you smoke overtime your arteries will get plaque buildup which makes it hard for your blood to flow freely through your arteries.
This can then lead to blood clots and then cause heart attacks, heart disease, strokes etc.
The structure of your blood vessels are also damaged in the process of smoking and your lung function also decreases and then you can eventually get lung cancer as a result of smoking.
Smoking can also cause shortness of breath, wheezing, coughing etc because your lungs become damaged from the inhalation of smoke.
Smoking is very bad for your health so if you want to stay healthy and increase your chances of living to 100 and beyond then smoking should never be done and if you do smoke you should quit now.