If you have been feeling sluggish or fatigued, you may want to consider the traditional Chinese mushroom cordyceps (Cordyceps sinensis). Long used in China as an energizing tonic for people debilitated by age, illness, or injury, it more recently has been used by athletes to help increase aerobic capacity and endurance. Cordyceps can help you to overcome general weakness and fatigue, and acts as a tonic for physical stamina and mental energy.
Wild cordyceps grows on the larvae of certain moths, and the preparation commonly used in China is the whole, dried mushroom attached to a mummified larva, often simmered in soup. In the United States it is available in tincture, powder and as a liquid extract - look for liquid or powdered extracts grown on grain, not grown on caterpillars. To address general weakness or fatigue, adults can take 1-2 capsules per day (or follow dosage advice on product); for health maintenance, take 1 capsule once or twice per week. Children should not take cordyceps.