Smoking injures blood vessels and speeds up the hardening of the arteries. The carbon monoxide in cigarette smoke reduces the amount of oxygen that your blood can carry. Secondhand smoke can increase the risk of stroke for nonsmokers.
Drinking too much alcohol raises your blood pressure, which increases the risk for stroke. It also increases levels of triglycerides, a form of cholesterol, which can harden your arteries.
Not getting enough exercise can make you gain weight, which can lead to increased blood pressure and cholesterol levels. Inactivity also is a risk factor for diabetes.