What's the difference between the London Marathon and coaching?

On 26th of April 2015 I ran the London Marathon.

As I pounded the streets a quote from David Nicholson's book, 'Think Like an Athlete.' popped into my head: 'Once an understanding of the transformative potential of running sinks in, it's just a matter of making the connections in other areas of life.' And it occurred to me that there are a host of similarities between running a long distance race, and gaining a professional coaching qualification.