The [Timex Ironman digital watch] comes with a box about the size of a pack of playing cards that you strap round your upper arm, which communicates with 12 satellites to pinpoint your exact position and calculate all the other statistics I’ve mentioned. I am not sure that the bloke who invented satellites realised that his invention would be used to check the progress of a plodding, fat man traversing the back streets of West London. He probably thought it would be used for international espionage, but he was mistaken.
We’re living in the future my friends! Link