What process does the carbon dioxide that you exhale come from?

The carbon dioxide you exhale primarily comes from the process of cellular respiration. In this process, cells convert glucose and oxygen into energy, producing carbon dioxide and water as byproducts. This carbon dioxide is then transported via the bloodstream to the lungs, where it is expelled during exhalation. Thus, the exhaled CO2 is a result of the metabolic activities that provide energy for the body.