A good friend from high school had a stroke at age 40. She was in good health, a non-smoker, and athletic. She has recovered well, and has no outward signs of having gone through it (though she has occasional memory issues and is now right handed instead of left handed (thanks to hard work with a good PT/OT crew.). Stroke took my dad at 54. Congenital veinous defect. Sucks. Age may not matter. Luck may matter more.