Tomorrow is London Marathon day.
Almost 40,000 runners will be taking on 26.2 miles or 42.2km ish.
Some say the best way to take on a marathon is to break it down to just two 10 mile runs with a 10km run at the end.
Last year i took part in a 10km race around central London, which was great fun. Not only did i get to run around some amazing landmarks in central London, i was also dressed as the Cancer Research UK shoe and filmed it all with my GoPro on a selfie stick.