Resveratrol is a chemical compound found naturally in blueberries, cranberries, grape skins and peanuts. Often touted for its fat-burning effects, resveratrol is also an energy booster. One of its methods of actions is increasing the number of mitochondria, or cellular power plants, in each muscle cell. Having more mitochondria in each cell means that your body can produce more energy, leading to better muscular endurance in the gym. In fact, one study from the Institute of Genetics and Molecular and Cellular Biology in France reported that mice given resveratrol had enough energy to run twice as far before reaching exhaustion as those given a placebo. Resveratrol also may help provide the most beneficial form of endurance — increasing your life span. For best results, take 50 to 500 milligrams of resveratrol on an empty stomach in the morning and another dose about 30 minutes before your workouts.