Swift sings, dances, and struts along a stage the length of a football field throughout the sparkling 3.5-hour affair, all while sporting an array of custom Christian Louboutin heels corresponding with each “era” of her career. It is, by any standard, a remarkable athletic feat, and Swift prepared accordingly.

“Every day I would run on the treadmill, singing the entire set list out loud,” Swift told TIME. “Fast for fast songs, and a jog or a fast walk for slow songs.”

Six months before the tour began, the 33-year-old started her intensive training at Dogpound, a celebrity-laden gym in New York City. In addition to running while singing for the three-plus hour length of each show — a span comparable to the timing of a marathon — Swift said her trainers crafted a plan that also incorporated weight lifting, strength training, and other forms of conditioning.

She tacked on “three months of dance training” as well.

“I wanted to get it in my bones,” Swift explained. “I wanted to be so over-rehearsed that I could be silly with the fans, and not lose my train of thought.”

“Learning choreography is not my strong suit,” she added.

Swift also cut alcohol out of her life, at least for the duration of the tour. Her lone exception was the “hilarious” night of the 2023 Grammy Awards, when she was visibly tipsy while dancing and singing along to the performances from her spot in the audience.

But aside from the awards show back in February, Swift steered clear of drinking, and for good reason:

“Doing that show with a hangover,” she told TIME. “I don’t want to know that world.”

By the time her stint in any given city comes to a close, Swift said she “can barely speak” from singing so much. Every time she takes a step, she added, she can feel her feet crunching under her “from dancing in heels” for a collective 10.5 hours.

Swift knows that she’ll force herself to perform regardless of “whether I’m sick, injured, heartbroken, uncomfortable, or stressed,” so she takes steps to keep up her strength and mitigate those risks. She makes sure to devote a full day to rest and recovery after each stop on the tour.

“I do not leave my bed except to get food and take it back to my bed and eat it there,” Swift said. “It’s a dream scenario.”