The key, IMHO, is to eat a moderate, balanced diet, with a mixture of the different food groups (fruits, vegetables, grains, meat & fish, dairy products), and avoid eating excess fat, not eating ZERO fat.
Limited to no added sugar
Limited to no added salt.
Limited to no processed grain [stick to whole wheat]
Fat consumption towards monounsaturated, keep the Omega 3 to 6 balance reasonable
Up that consumption of veg
Up that consumption of fiber
Do that and
Exercise even minimally, both cardio and weights
Maintain a modest or lower bodyfat content.
Fist your self in a playground while wearing nothing but a gas mask and fur boots daily
Don't smoke [and really, do I have to mention the crack and the crystal meth?
Sure the diet would require a bit of research, but do the above and unless you are one of those poor saps who come from a family where every dies in their 40's from a heart attack, you should be able to do very well. Any additional rules would probably get you minimal extra benefit unless you have some sort of allergy or other food issue
If everyone were to do this from their early days, there would be a lot of unemployed cardiologists, Type 2 diabetes would be extremely rare, and rates of cancer arthritis and other assorted nasties would drop a bit.