In less than a week, reigning Australian Open champion Angelique Kerber will take to the courts at Flushing Meadows to begin her bid for her second Grand Slam title of the year. Also at play? A chance to become WTA World No.1.

The 28-year-old is having the best year of her career, and she admits that she owes much of her late renaissance to her improved fitness.

“Right now I’m one of the fittest players in the world,” Kerber told CNN. “It’s strange, but it helps you really reach your goals at the end.”

CNN Open Court went inside the gym with Kerber to discuss how she gets Grand Slam fit, just in time for the final Slam of the year.