New York Times has an excellent in depth review of anemia which everyone should read.

Thanks to advertisements for the once-popular tonic Geritol, most people of a certain age know about “tired blood,” a disorder more accurately called anemia, involving a shortage of healthy red blood cells to carry oxygen to body tissues and cleanse them of carbon dioxide.

Reference: Anemia - Reporter’s File - ‘Tired Blood’ Warning: Ignore It at Your Peril - NY Times Health

The red blood cells of a person suffering from anemia (right) are a very light pink when stained, and they are often less round and full when viewed under a microscope. The round, plump bodies of normal red blood cells (left), when stained, are a bright pinkish-red. Hemoglobin is the substance that gives normal cells their bright color.

Reference: Anemia | medical health