Pope Francis acknowledged Saturday that he can no longer travel like he used to because of his strained knee ligaments, saying his week-long Canadian pilgrimage was “a bit of a test” that showed he needs to slow down and one day, possibly retire.

Speaking to reporters while travelling home from northern Nunavut, the 85-year-old Francis stressed that he hadn't thought about resigning but said “the door is open” and there was nothing wrong with a pope stepping down. “It's not strange. It's not a catastrophe. You can change the pope,” he said while sitting in an airplane wheelchair during a 45-minute news conference. Francis said that while he hadn't considered resigning until now, he realises he has to at least slow down.