If you find yourself becoming exhausted after an activity that used to be easy -- for example, walking up the steps -- it may be time to talk to your doctor about the possibility of heart disease. If your fatigue is related to your heart, medication or treatment procedures can usually help correct the problem, reduce the fatigue, and restore your energy. This is a diet in which you cut out certain foods that cause a variety of symptoms, including sleepiness within 10 to 30 minutes of eating them. You can also talk to your doctor about a food allergy test -- or invest in a home test such as ALCAT -- which may help you identify the offending foods. As you become accustomed to the added physical activity, you can increase your time in the pool or gym.