Adherence

In men with pre-existing ischaemic heart disease, increasing physical activity does not consistently reduce heart attack risk and may increase it, although it reduces case fatality.

If you have known heart disease, do not simply increase your activity level assuming it will prevent heart attacks. This study suggests higher activity might actually increase risk in this group, though it helps you survive an event better. Consult a doctor for a tailored, likely lower-intensity regimen.