If you manage the factors that damage your arteries or together with your doctor you manage the other risk factors that could cause blood clots, you can to a large extend prevent stroke from happening.
Smokers inhale many harmful gasses. These gasses could increase your blood pressure and damage your arteries making them hard and inelastic, which could lead to stroke. Your body can heal the damaged arteries if you allow it. If you stop smoking, your blood pressure recovers from nicotine spikes after just 20 minutes. After 1 year, your risk of artery disease is cut in half.