updated 01/21/2014 AT 11:00 AM ET
•originally published 01/22/2014 AT 7:35 AM ET
Fifty years ago this week, Sports Illustrated debuted its first annual swimsuit issue – making what was once a niche sports publication one of the most buzzed-about magazines around.
While the Swimsuit Issue began as a five-page insert to the magazine, by 1997 it had become a stand-alone issue that has raked in more than $1 billion to date. According to Forbes, it remains the most profitable single edition of any magazine in the world.
While the pages of the SI Swimsuit Issue have featured many well-known models, including Cheryl Tiegs, , , Christie Brinkley and Kate Upton, the best-selling issue of all time is 1989’s 25th anniversary edition featuring Kathy Ireland on the cover.
In this behind-the-scenes video, Ireland reveals some of her secrets to working under tough conditions as they shoot the swimsuit edition:
Ireland was featured in a whopping 13 consecutive years of the Sports Illustrated Swimsuit Issues, including three covers – one when she was pregnant. While her record is certainly impressive, her accomplishments since leaving the modeling world are even more inspiring.
In addition to being a mother of three, Ireland, 50, has built a mega-business out of her personal brand. After giving Hollywood a whirl, finding roles in dozens of television shows and films, the supermodel found ultimate success in the boardroom.