January 2010: I waved goodbye to my family and friends from outside St Thomas’ Hospital in London, where I worked as a medical doctor, and set off on my bicycle. My plan was to cycle the length the six continents. On that first day, I didn’t get far. I pedalled off. I made a quiet U turn. I headed to the pub. And then I hunched over a pint, fraught with self-doubt, whilst my loved ones supposed I was pedaling towards France.

Hours passed. The world I’d pedalled into was too big. I was unfit and under-prepared and feeling ungrateful for breezing away from a profession I loved, interesting friends and a comfortable life. Several curry houses knew me by my first name. I enjoyed a frappe.

Eventually, without coming up with a good excuse not to go, I set off into the night, and the dawning of the coldest European winter for thirty one years. 86,209 km (53,568 miles) later I emerged onto Westminster Bridge having cycled a distance equivalent to more than twice around the planet or 89 times the length of Great Britain.