When we get run down and are lacking in energy, it's not that there is no reason for it. In the case of adrenal exhaustion, cortisol, the stress hormone is depleted from chronic stress. This is well known in herbal medicine, and traditionally there have been powerful herbal treatments. Ginseng is an example of such a herb.
Other common reasons for fatigue are vitamin and mineral deficiency. Also supplementation with agents involved directly in energy production in the cells like Coenzyme Q10 can often help.
The B vitamins are involved with glucose metabolism required for energy production. Zinc is required by many enzymes, some of which are important for metabolsim.
Magnesium is required for ATP synthesis. ATP provides energy in the cells.
Iodine is required by the thyroid gland. An underactive thyroid gland results in low metabolism. Iodine is found in kelp, spirulina and chlorella.
Potassium found in fruit and vegetables is also required for energy.