New business ideas can come from almost anywhere. Sara Blakely’s bright idea was behind her the whole time—literally.

In 1998, the founder and former CEO of the women’s shapewear brand was working as a fax machine salesperson when she got the inspiration for Spanx. Her white pants had hung in her closet for eight months without wear because she couldn’t get the “smooth look” she wanted. Blakely, then in her mid-20s, wanted to wear something that wouldn’t show panty lines and came without the bulk of the classic girdle—so she cut the feet off control-top pantyhose.

With that, Blakely had come up with the idea that would eventually make her a billionaire .

“I wanted my clothes to fit better, and so my own butt was the inspiration,” Blakely said during Fortune ’s 2013 Most Powerful Wo

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