Potassium: As a major electrolyte lost in sweat, replacing potassium after a workout is crucial. Allows your body to maximally get as much use out of the glucose inside of cells for energy. Without enough potassium, your body will slow down with muscles fatiguing sooner. Good sources of this mineral can be found in bananas, squash, avocados, spinach, and white beans.
Magnesium: Magnesium helps with hundreds of chemical reactions within the human, including allowing the muscles to access glucose and oxygen needed when exercising. We sweat this mineral out during a workout, so it is lost very easily. Foods with a good source of magnesium include nuts and seeds, dark leafy greens, brown rice, avocado, yogurt, and dark chocolate. Watch out for drinking too much alcohol or caffeine, because this can drop your levels of magnesium as well.
Iron: Iron allows the body to take oxygen from the blood that we need when working out. It is especially essential for longer duration workouts that are more intense. Low iron levels will cause fatigue, but too much iron can cause you to feel tired as well, so monitoring iron intake is essential. Iron rich foods include red meat, cereals, dark leafy greens, beans, and seafood.