Ncuti Gatwa is opening up about why he left “Doctor Who” after only two seasons.

In a new interview on the BBC’s “Sunday With Laura Kuenssberg,” the “Barbie” and “Sex Education” star was asked his reasoning for stepping away from the iconic sci-fi show.

“Because I’m getting old and my body was tired,” Gatwa said, adding that the show “takes a lot out of you — physically, emotionally, mentally. So it was time.”

However, when Kuenssberg questioned if he’d ever return to the Tardis one day — like David Tennant did recently — Gatwa quipped, “Never say never.”

It was revealed that Gatwa’s time as the Doctor was over in May, during the finale of the show’s second season as a co-production between the BBC and Disney+. Gatwa’s Doctor was regenerated into Billie Piper, who previously played companion Rose Tyler in 2005 and 2006. What Piper’s return means for the series has not been detailed, and it has not yet been renewed for a third season by the BBC and Disney+.

Gatwa is making the press rounds for his latest theater endeavor, the play “Born With Teeth” in which he stars as playwright Christopher Marlowe alongside Edward Bluemel’s William Shakespeare. It’s set to premiere in London on Aug. 13. In an interview with The Guardian, Gatwa called playing the Doctor “a gift of a job,” though he had to get “quite good at shutting the noise out.”

“It’s loud. But it’s very cool and exciting to be in the middle of this huge thing – there’s haters, there’s lovers, it’s all going on,” he said. “It is an absolute gift of a job, and a gift of a community. The Whovians are so deeply in my heart, I can’t tell you.”

Gatwa said while at Glastonbury Festival, he bumped into fellow former Doctor Matt Smith “in a club” and the two bonded over the experience. “We had great, deep chats about that job and how there’ll never be another like it in our lifetimes,” he said. “We’ll never work that hard again. Never be as stimulated and stretched. It’s also very exhausting, so it’s lovely to delve into other projects.”