What Is Heart Failure?
Heart failure, or chronic heart failure (CHF) is when the heart’s ability to function optimally is significantly impaired. It is indicated by the heart’s chronic inability to supply necessary amounts of blood, or pump blood hard enough, to distribute oxygen to the entire body.
The body’s ability to compensate often masks early warning signs of heart failure, causing the condition to go unnoticed by the patient until symptoms worsen.
At first, in an attempt to pump harder in response to the body’s increased demand for blood, the heart stretches. Overtime, this stretching causes the heart to enlarge. The body also compensates by narrowing blood vessels to keep blood pressure up and make up for the heart’s lack of force output. Further, blood is diverted away from other tissues and organs (like the kidneys), and towards the heart and brain. 
Eventually, blood backs up in the body’s veins, and fluid builds up, causing swelling of the feet, ankles, and legs (edema). Fluid also begins to build in the lungs (pulmonary edema). Symptoms mount, such as general, lasting fatigue; coughing and wheezing; weight gain; and confusion. At this point, patients often visit the doctor, where they are diagnosed with chronic heart failure. 
Approximately 90% of heart failure patients die from cardiovascular causes. 50% die from progressive heart failure, and the remainder die suddenly from arrhythmias and ischaemic events. Autopsy reveals the presence of an acute ischaemic event in approximately 50% of sudden deaths and in 35% of all deaths among patients with ischaemic heart failure. 
CHF is the #1 cause of hospitalizations for those over 65, and half of hospital readmissions are related to ongoing complications and disabilities related to CHF. A lack of adequate research in the treatment of CHF means patients, once diagnosed, have a difficult time reversing or improving symptoms. 
Unlike other heart disease risk factors like high blood pressure or high cholesterol, we don't have specifically effective drugs to prevent heart failure, so we need to identify and verify effective strategies for prevention and emphasize these to the public. 
How Do You Reduce The Risk Of Heart Failure?
Exercise. Increasing physical activity to the recommended 150 minutes of moderate to vigorous activity per week can reduce the risk of heart failure by 31%. In contrast, this same study demonstrated that a lack of exercise was linked to an increased risk of heart failure. 
Researchers arrived at their conclusions by analyzing the physical activity levels of more that 11,000 American adults in middle age.
"In everyday terms our findings suggest that consistently participating in the recommended 150 minutes of moderate to vigorous activity each week, such as brisk walking or biking, in middle age may be enough to reduce your heart failure risk by 31 percent," says Chiadi Ndumele, M.D., M.H.S., the Robert E. Meyerhoff Assistant Professor of Medicine at the Johns Hopkins University School of Medicine, and the senior author of a report on the study. "Additionally, going from no exercise to recommended activity levels over six years in middle age may reduce heart failure risk by 23 percent." 
This study is groundbreaking in that it shows that even if you went most of your life without exercising, your decision to start in middle age can still significantly improve your health and longevity.