Following a six-day voyage across Canada that included five stops and nine public appearances in Edmonton and Quebec City, Pope Francis said on Saturday that the trip will result in reduced future travel and even the possibility he may choose to someday retire.

It was during the customary papal news conference aboard the plane returning to Rome that Francis spoke candidly, offering a blueprint of what the remainder of his papacy might look like.

“I don’t think I can go with the same pace of the trips as before,” he told reporters aboard the ITA Airways flight. “I think at my age and with this limitation, I have to save (my energy) a bit to be able to serve the church or, on the contrary, think about the possibility of stepping aside. This I say with all honesty.”

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The pope conducted the 45-minute news conference while seated in a wheelchair.

Talk that Pope Francis could retire has been swirling for weeks. While he has danced around the issue in the past, Francis’ latest comments to reporters are the first real indication that his trip to Canada has taken a toll.

The pope traveled to Canada to personally apologize to the the country’s Indigenous communities for the Catholic Church’s role in forcibly converting them, leading to generations of physical and sexual abuse in residential schools.

The pontiff spent a good part of the trip either seated or moving around in a wheelchair due to a bad right knee. The pope called the trip to Canada “intense.”

“I think I have to limit myself a bit with these exertions,” he said. “Knee surgery for me is not an option in my case. The health care professionals say it is, but there is the whole problem of anesthesia. Ten months ago, I underwent more than six hours of anesthesia, and there are still traces.”

Pope Francis underwent general anesthesia last year during surgery necessitated by a stenosis, or narrowing, of the sigmoid portion of the large intestine.

Despite his poor health, the pope said he still plans to travel to Kazakhstan in September for an interfaith conference. There, he could also meet with Russian Orthodox Patriarch Kirill, who has justified Russia’s military intervention in neighboring Ukraine.

Regarding a timeline to when he could retire, should he choose that route, the 85-year-old pope said, “The door (to retirement) is open. It is a normal option. Until today, I have not knocked on that door. I have not felt the need to think about this possibility. That’s not to say that in two days' time I might not start thinking about it.”

Prior to Francis’ election, former Pope Benedict XVI resigned from the papacy in 2013 — and as a result took on the emeritus moniker — eight years after he was elected by the College of Cardinals. The unexpected resignation came after Benedict cited a “lack of strength of mind and body” due to his age. He was 86 at the time. In doing so, he became the first pope to resign since Gregory XII in 1415 and the first to do so on his own initiative since Celestine V in 1294.

“It is not a catastrophe,” Francis told reporters. “It is possible to change pope.”

During the same news conference, the pope was asked about traditional Catholics — people who have been most at odds with Pope Francis over the past few years — within the church.

The pope, who has fancied himself a progressive, has angered many conservative Catholics. Last year, he quashed the old Latin Mass, forbidding the celebration of some sacraments according to the ancient rite.

In statements that will likely anger traditionalists further, Francis told reporters he’s open to developing a doctrine centered around the use of contraception. Church teaching currently prohibits the use of contraception.

“Tradition is the living faith of the dead,” the pope insisted. “Instead, their attitude is the dead faith of the living.”

Clemente Lisi is a senior editor and regular contributor to Religion Unplugged. He is the former deputy head of news at the New York Daily News and teaches journalism at The King’s College in New York City. Follow him on Twitter @ClementeLisi.