You've seen such lists before: 5 steps to prevent heart disease or some such thing. These lists usually say things like "cut your saturated fat," eat a "balanced diet" (whatever the heck that means), exercise, and don't smoke.
I would offer a different list. You already know that smoking is a supremely idiotic habit, so I won't repeat that. Here are the 5 most important strategies I know of that help you prevent heart disease and heart attack:
1) Eliminate wheat from the diet--Provided you don't do something stupid, like allow M&M's, Coca Cola, and corn chips to dominate your diet, elimination of wheat is an enormously effective means to reduce small LDL particles, reduce triglycerides, increase HDL, reduce inflammatory measures like c-reactive protein, lose weight (inflammation-driving visceral fat), reduce blood sugar, and reduce blood pressure. I know of no other single dietary strategy that packs as much punch. This has become even more true over the past 20 years, ever since the dwarf variant of modern wheat has come to dominate.
2) Achieve a desirable 25-hydroxy vitamin D level--Contrary to the inane comments of the Institute of Medicine, vitamin D supplementation increases HDL, reduces small LDL, normalizes insulin and reduces blood sugar, reduces blood pressure, and exerts potent anti-inflammatory effects on c-reactive protein, matrix metalloproteinase, and other inflammmatory mediators. While we also have drugs that mimic some of these effects, vitamin D does so without side-effects.
3) Supplement omega-3 fatty acids from fish oil--Omega-3 fatty acids reduce triglycerides, accelerate postprandial (after-meal) clearance of lipoprotein byproducts like chylomicron remnants, and have a physical stabilizing effect on atherosclerotic plaque.
4) Normalize thyroid function--Start with obtaining sufficient iodine. Iodine is not optional; it is an essential trace mineral to maintain normal thyroid function, protect the thyroid from the hundreds of thyroid disrupters in our environment (e.g., perchlorates from fertilizer residues in produce), as well as other functions such as anti-bacterial effects. Thyroid dysfunction is epidemic; correction of subtle degrees of hypothyroidism reduces LDL, reduces triglycerides, reduces small LDL, facilitates weight loss, reduces blood pressure, normalizes endothelial responses, and reduces oxidized LDL particles.
5) Make exercise fun--Not just exercise for the sake of exercise, but physical activity or exercise for the sake of having a good time. It's the difference between resigning yourself to 30 minutes of torture and boredom on the treadmill versus engaging in an activity you enjoy and look forward to: go dancing, walk with a friend, organize a paintball tournament outdoors, Zumba class, plant a new garden, etc. It's a distinction that spells the difference between finding every excuse not to do it, compared to making time for it because you enjoy it.
Note what is not on the list: cut your fat, eat more "healthy whole grains," take a cholesterol drug, take aspirin. That's the list you'd follow if you feel your hospital needs your $100,000 contribution, otherwise known as coronary bypass surgery.