If you are constantly feeling exhausted doctors will tell you that you might have anemia. Anemia can be a tough diagnosis though.
Some people are anemic without any symptoms and others have all the symptoms without being anemic.
Symptoms or not, most people with anemia tend to have simple iron deficiency anemia. Your body uses iron to manufacture red blood cells. If your iron levels drop, then your body loses its ability to manufacture red blood cells. The lower the number of red blood cells, the lower the amount hemoglobin. As hemoglobin drops, the ability of the blood to carry oxygen drops.