Why Professor Larry Smarr freezes his own faeces
Increasingly, people around the world are monitoring more and more about their daily lives, helped by smartphone apps and gadgets.
Professor Larry Smarr is one of the most influential computer scientists in the United States.
He was instrumental in developing networked computers - the predecessors of the internet.
Today, he puts his energies into monitoring everything about himself, from his calorific burn and heart rate to his saliva, urine and even his faeces.
Professor Smarr explains to Horizon presenter Dr Kevin Fong why he believes we are flushing away a vital source of personal data every day.
Horizon: Monitor Me, Monday 12 August, 9pm, BBC Two.
12 Aug 2013