She said: “I think the energy that I felt on that tour, it was so big and infectious, and I wrote most of this while I was on that tour. So it’s like I would go from three shows in a stadium, fly to Sweden, fly back to the tour, fly to Sweden.
“And it sounds like sort of an impossible feat or a ridiculous challenge to take on, but at that point in the tour, I was so physically exhausted that I kind of needed to get back in that creative space and that fuelled me past physical exhaustion.”
Swift admitted there were times when it felt like the “really complex” concerts were something she needed to “survive”.
She said: “Really, every time I would just collapse into bed at night after the show, I’d just be like, I take the longest, deepest sigh of just like, we managed to do it again.
“It’s a show you have to like survive. Every now and then I’m like ‘We survived it again.’ ”
