Andrew Murray has been running since 2005 when he realised that it might be a good way to see a bit of the world.
Since then he has been placed first overall in races in the Arctic, the Sahara, Outer Mongolia and the jungle, amongst others.
But in 2010 he devised a challenge that put all his previous attempts in the shade - to run from Scotland to the Sahara in one continuous push with no rest days!
It is 2,659 miles from John O'Groats at the northern tip of mainland Britain to Merzouga in Morocco and Andrew planned to complete the distance in 85 days.
That's the equivalent of 100 marathons run end to end - and not a single day off to recover.
With minimal support, and in the middle of winter, trying to run an ultra marathon every day was the challenge of a lifetime for Andrew.
As a medic, Andrew knew exactly what that would do to his body...and it wasn't good news.
Attempting to cram in a staggering 8,000 calories every day is extremely difficult and doesn't stop the body from beginning to break down.
This book is the story of that run, interwoven between tales of extraordinary endurance events in some of the most extreme locations in the world. It answers the question, 'why do it?', and offers a gripping insight into what drives an extreme athlete to break new ground.
Helped by family, friends, those he meets along the way, and a fiancee he's shortly to marry, this is the story of one man's determination to run in the history books. Andrew Murray's epic journey was the subject of a highly successful BBC documentary and this book is the inside story of what pushes one man to keep breaking the limits.
Even a planned 85 days wasn't enough to satisfy Andrew - in the end he completed the distance in just 78 days.
The book is introduced by Sir Ranulf Fiennes.