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The Olympian and reality television star has been at the center of the media spotlight for months now over his rumored gender transition.
"My whole life has been getting me ready for this," Jenner tells Sawyer in the clip.
Watch the 2-hour Bruce Jenner: The Interview on ABC on Friday, April 24 at 9 p.m. ET | 8 p.m. CT.
PHOTOS: Bruce Jenner lists Malibu home