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.
Being physically active strengthens everything in your body ranging from your bones, your muscles, but also your heart, your lungs, and your arteries. Physical activity could result in lower blood pressure and helps you get rid of excess sugar or cholesterol, which might be hanging around in your blood waiting to damage your arteries.
30 minutes of any activity that increases your heart rate, 5 times a week is recommended, but do not be intimidated. Anything is better than nothing, so get off the chair and mow the lawn or play hide and seek with your child, both of you will benefit.