Hot hot heat. Taxi engines buzzing and horns blaring. Kids selling packs of gum to tourists, a bored Mariachi band knocking out a Mexicana version of Hotel California for the 100th time of the day while a donkey, painted as a zebra, looks on. Welcome to Tijuana.

We were halfway through the trek when the first sign of trouble arrived. I looked down at my boot. A slug uncoiled, extended an inch and, moving like a slinky, began climbing. Flicking it off, I spotted another on my sock. As I went to launch it into jungle oblivion, it vanished through the cotton. Panicking, I pulled the sock down to find, clamped to my flesh, a leech.

You know that poor soul stood outside the train station no matter how bad the weather is? Their eyes lighting up like a fruit machine when you appear? Then, as you pass by, BANG, there’s a free paper in your hand whether you wanted it or not. Well, show them some respect next time. It's tough out there on the streets.

Mankind is capable of incredible feats of endurance. Climbing cliffs without ropes. Running marathons across deserts. Swimming through shark-infested oceans. And even watching an entire Jason Statham film. But very few people have the mental strength, discipline and willpower required to survive a 3-day journey on a Greyhound bus.