A person's likelihood of a heart attack is calculated in large, population-based studies. We know of many of the risk factors that make a heart attack more likely, and high blood pressure and "bad" cholesterol (high LDL, low HDL) are two important ones. Cigarette smoking, family history of early coronary disease, and diabetes (even pre-diabetes) are three other important risk factors. There are probably other risk factors that we don't understand yet or know how to measure, like: how resistant is the vessel wall to cholesterol build-up?
So there are people with many risk factors who don't have CAD (Coronary Artery Disease), and some people with minimal risk factors who do have CAD and have had heart attacks. The probability of having a heart attack is higher the more risk factors you have.
An analogy would be to ask and answer the question "What is the risk of my having an accident while driving from SF to LA?" If you're driving the safest car, at the speed limit, paying close attention, and you are a very good driver, the risk is much lower. However, if you're going 80 mph and texting while driving, you have greatly increased your risk. But even the best driver can get into an automobile accident, and the worst driver can get there safely.
We only can control what we can control. I might suggest you look into why you get shortness of breath upon exertion. Is it just deconditioning and obesity, or is it from a heart or lung problem?
We all should do what we can to improve our overall health - which allows us to enjoy life as much as we can, and be around longer. That takes a partnership between you and your health care team.