Answer: Handwashing. It is estimated that washing hands with soap and water could reduce diarrheal disease-associated deaths by up to 50% 1. Researchers in London estimate that if everyone routinely washed their hands, a million deaths a year could be prevented 2.
Thats burning of glucose as fuel in the cells. It generates heat and is an exothermic reaction. In Mitochondria, which act as furnaces, the fuel helps generate heat for the cells of the body.