So you want to...run a marathon

Running a long, long way. What it is:

The modern marathon is run over 26.2 miles or 42.195 kilometres. It is the only discipline in athletics to have become a popular participation sport. After 20 miles many inexperienced runners hit ‘the wall', an infamous experience suffered when their bodies have run out of fuel.

A popular nutty chocolate bar of the 1980s. What it's not:

First-time marathon runners should follow a specific programme ...