In 2012 Alastair rowed across the Atlantic Ocean.

A 16-foot canoe loaded with food, 500 miles of wilderness ahead of us, camping on islands under the stars: paddling down the Yukon River remains one of my favourite adventures.

My head is thumping. My eyes are stinging. I’m weak with thirst.

The Marathon des Sables is known as “the toughest race on Earth”, running with all your food and kit for 150 miles through the Sahara desert.