Sara Blakely cut the feet off her tights and built Spanx

In 1998 Sara Blakely wanted to wear white trousers without visible lines underneath. Pantyhose made her feet sweat and looked wrong in open-toed shoes.

She was 27 and selling fax machines door-to-door for Danka. That night she took a pair of control-top pantyhose and cut the feet off with scissors.

The cut edges rolled up by the end of the evening. It still worked better than anything she could buy.

Blakely was not a fashion designer. She had no business degree and had never worked in manufacturing.

Her plan had been law. She failed the entrance exam twice.

The fax machine job was cold calls and rejection, all day, then again the next day. She has since described it as the best training she could have had, because rejection stopped frightening her.

Her father had prepared the ground. At dinner he asked his children what they had failed at that day, and was disappointed when the answer was nothing.

She had about $5,000 saved. No venture capital, no angel investors, no wealthy family.

She researched hosiery patents in public libraries, taught herself the basics of intellectual property law and wrote large parts of her own patent application herself.

Manufacturer after manufacturer turned her down. Footless shapewear was not, in their view, a product.

A hosiery mill owner in North Carolina eventually called back. He had gone home grumbling about a persistent inventor and his daughters told him they would buy it.

Production started. Nobody had heard of her.

Blakely walked into Neiman Marcus without an appointment. The buyer was unconvinced, so Blakely asked to use the ladies' room, put the product on and invited the buyer in to look at the mirror.

Neiman Marcus placed an order. Bloomingdale's and Saks followed.

In 2000 Oprah Winfrey named Spanx one of her Favourite Things. Demand jumped within hours.

That is the part people remember, and it sat on two years of rejections nobody televised.

Blakely built the brand around playful packaging, humorous copy and bright red, in a category built on insecurity. She wanted customers to smile at the till.

She also kept saying no. Private equity firms, banks and advisers came calling and she retained control, accepting slower growth in exchange for not explaining herself to a board every quarter.

In 2012 Forbes called her the youngest self-made female billionaire. She kept talking publicly about the rejections rather than tidying them out of the story.

She has since signed the Giving Pledge, committing most of her fortune, and funded scholarships for women and investment in other founders.

For a founder reading this, the useful part is not the billion. It is the sequence.

Spanx did not begin with market analysis. It began with an everyday irritation and a pair of scissors, and it survived because the founder had already spent years being told no by strangers on the phone.

Confidence did not come first. Action did.