context: Atrial fibrillation ( AFib) is a problem with your heart's rhythm -- it can beat too fast or too slow, and in a chaotic way. That prevents it from pumping blood as well as it should. That could cause serious health problems, called complications. Your doctor has treatments to put your heart back into a normal rhythm and prevent complications. Normally when your heart beats, the two upper chambers -- called atria -- squeeze and push blood into the two lower chambers -- called ventricles. In AFib, the atria quiver instead of squeezing strongly. So they push only some of the blood into the ventricles. That means blood can pool inside the heart. Clumps of blood called clots can form there, too. A clot that forms in the atria can travel to the brain. If it gets stuck in an artery, it can block blood flow and cause a stroke. AFib medicines bring your heart back into a normal rhythm, prevent blood clots from forming, and lower the odds you'll have a stroke. High blood pressure can also lead to strokes. So it's even more important to keep your blood pressure in a healthy range with a nutritious diet, exercise, and medicine if you need it. AFib makes the ventricles beat faster to push blood out of the heart. Beating too fast for a long time can make the heart muscle too weak to pump enough blood to your body. This is called cardiomyopathy. Medicines for AFib like beta-blockers and calcium channel blockers slow your heart rate. These drugs can help prevent cardiomyopathy. AFib prevents your heart from pushing out blood as well as it should. After a while, the effort of pumping makes your heart so weak, it can't send out as much blood as your body needs. This is called heart failure. Blood can get backed up in the veins of your lungs and cause fluid to build up there. That causes symptoms like fatigue and shortness of breath. To lower your chances of getting heart failure, manage these four key things: Keep your blood pressure in a normal range. Stay at a healthy weight with diet and exercise. Don't smoke. Control your blood sugar if you have diabetes. Your body needs a steady supply of oxygen-rich blood to work properly. When your heart can't pump enough, you'll feel tired. If fluid builds up in your lungs because of heart failure, that can add to your exhaustion. To manage fatigue, balance your activities with periods of rest. Try to get more sleep at night. And exercise as often as you can. A combination of aerobic exercises like walking and biking, plus strength training can give you more energy. Sleep apnea could be another reason why you feel extra tired. This condition, which keeps you from breathing properly when you sleep, can happen along with AFib. Your doctor can test you while you sleep to find out if you have it. One treatment for sleep apnea uses a machine called CPAP, which delivers mild air pressure through a face mask to keep your airways open while you sleep. In studies, people with AFib did worse on memory and learning tests than those without the condition. Dementia is also more common in people with AFib. One possible reason for the link is that AFib raises your odds for a stroke, which can damage the brain. AFib might also affect memory by keeping the brain from getting enough blood. Your doctor might recommend that you take blood thinners like aspirin and warfarin to prevent a stroke. Lifestyle changes that protect your heart -- including weight loss -- could also protect your brain. A few healthy habits can help you avoid the other health problems that AFib can cause. Eat a heart- and brain-healthy diet. Limit salt, and saturated and trans fats. Make fruits, vegetables, whole grains, and lean protein the majority of your diet. Exercise on most days of the week. Ask your doctor to recommend a fitness plan that's safe for your heart. Manage blood pressure and cholesterol with diet, exercise, and medicine if you need it. If you smoke, ask your doctor for advice on how to quit. Limit alcohol and caffeine.