Want to be ready for your big moment? Then don’t skimp on practice.

So says Taylor Swift, who revealed how she prepared mentally and physically for her record-shattering The Eras Tour. Six months before the first show, she got serious about getting into peak condition.

“Every day I would run on the treadmill, singing the entire set list out loud,” she told Time. “Fast for fast songs, and a jog or a fast walk for slow songs.” (For those keeping track, that’s over 180 minutes of running and singing.) Then she said she put herself through three months of dance training, explaining that she “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.”

Sounds grueling, and it is. Practice and training are not fun, but experts say that the physical and mental advantages of a “practice, practice, practice” mentality are monumental. Apart from the obvious skill and fitness improvements repetition brings, it is also key to building confidence. As executive coach and host of the She Believed She Could podcast Allison Walsh wrote in Entrepreneur, “Nothing boosts your confidence more than knowing that you’re prepared.”

Practice gives you the confidence to perform, and the foundation of muscle memory will give you the courage and capacity to pivot in the moment when needed. It’s the same philosophy that Special Operators like Navy SEALs do dry runs of missions as much as possible. If you can execute the plan in your sleep, you can go off script if circumstances require it.

Now, most entrepreneurs aren’t going to find themselves singing for hours in front of thousands of people every night, but Swift’s approach can pay off big in business. Netflix co-founder and star of “Entrepreneur Elevator Pitch” Marc Randolph explains: “Whether it’s getting a venture capitalist to invest a million dollars, convincing a key hire to come on board, crushing that interview with the New York Times, or just explaining to your parents why you’re dropping out of school to pursue your dream…you need to be able to do it confidently, comfortably, and persuasively. And there’s only one way to be great at it. You’ve got to practice. A lot.“