My family has a terrible history of heart disease
- dad died at 56 (otherwise the healthiest man on the planet), his mom at 46, my uncle has had triple bypass twice, and my aunt has had 3 heart attacks. Trust me, I am way concerned about this too.
If you have a family history, speak to your doctor. Get a complete cholesterol
work up and it's not a terrible idea to go ahead and get a blood pressure machine (a nice one costs about $40 or $50) and keep tabs on that too. Don't smoke, eat healthy, and exercise. Cardio workouts are the best as they help with something having to do with how your blood travels through your arteries (I'm not a technical person with medical stuff). I think one of the best diets to follow is the standard Harvard Food Pyramid - http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/pyramid/
It's an easy diet to maintain and all around very healthy.
It's smart for you to take heart disease seriously. One more thing, and this is really the most important - see your doctor regularly. My father would still be alive today if he wasn't such a dipwad. He refused to see a doctor.