If getting to every country was challenging enough, then finding a scenic route to run upon arriving proved impossible.
Often it was just a matter of running laps over and over again -- 82 in Vatican City, 104 in the high commissioner's compound of the British Embassy in Kingston, Jamaica, and 105 inside a stadium in the Syrian capital Damascus.
But the most laps? A mind-numbing 335 in a hotel carpark on the Pacific nation of the Marshall Islands, where Butter couldn't escape packs of feral dogs.
"We didn't plan on dogs being such a problem, but dogs were the bane of my life," he says. "After a dog bite in Tunisia, I was conscious that if they nipped my Achilles or something, then that is really game over.
"When I checked into my hotel in the Marshall Islands, they gave me my key and a stick and said, 'If you go outside, you'll need the stick.' There's actually a big diabetes crisis on the island -- people don't walk because it's so violent with the dogs.
"I was surrounded by these big dogs and I had to turn back and run in the hotel car park, which was about 120 meters, something like that. And it was just round and round and round those 335 laps of the carpark. Terrible."
Butter had identified 15 "problematic" countries before leaving -- "anything from Iran, to Afghanistan, to Somalia, to Yemen, to Syria, to Libya" -- and he recalls crossing a roadblock on the border of Syria and Lebanon where people had been killed just days before he passed through.
Temperatures ranged wildly -- from wearing six layers for his first run in Toronto, to battling 60-degree heat in Kuwait where he drank nine-and-a-half liters of water on his run.
Food was also an issue. Butter says he went 35 days without eating having run a marathon, and calculates he lost 11 kilos in the first two weeks of his African leg, weight he put back on by eating double meals on planes.
"I'm very, very sick of plane food," he adds.