Even if you follow all the best health habits to the letter, you can't control every variable. Genetics (family health history) plays a huge part in our fate, and those factors are totally out of our control.
Therefore, be sure to get regular checkups and all recommended screening tests for your age and gender. Pay attention to your body and don't ignore feelings that you know in your gut aren't right. In the spring of 2010 I noticed rather suddenly that my usual exercise routing caused a great deal of fatigue. If I walked up one of the hills in my neighborhood as I'd done countless times before, it seemed as though I were trying to scale Everest. So I'd drive to a flatter part of my 'hood and try to get my exercise there; even that had me out of breath within a short distance. Long story short: two of three major arteries were 90% or more blocked and I ended up with four stents in those arteries. It was shocking, but not surprising given my family history (dad dead at 58 of heart disease, brother with triple-bypass in his early 50s).
So even those of us good health habits can have life-threatening health challenges well before old age. Never take your good health for granted!