These entrepreneurs are leading 8 of the fastest-growing new retailers in the world - and now Tony Robbins and Tim Ferriss will help

• Shopify announced eight winners of its inaugural "Build a Bigger Business" contest.
• UK-based Gymshark took the top spot, with £41 million in annual sales and 215% YOY growth.
• Winners will have group and personal mentoring from high-profile coaches including Tony Robbins and Tim Ferriss.

The founders of eight of the fastest-growing online retailing startups are headed to Tony Robbins' Fiji resort, Namale, this week.

They'll be getting group and personal mentoring from a celebrity cast of coaches that includes Robbins, Tim Ferriss, Daymond John, and Marie Forleo.

They are the winners of Shopify's first "Build a Bigger Business Contest," an offshoot of its popular "Build a Busines" competition series. Shopify is an Ontario-based tech company that provides entrepreneurs with an online retail platform. It partnered with Ferriss in 2008 when Ferriss pitched the idea of starting a competition for new startups using the Shopify platform.

The annual prize evolved from minimal funding to in-depth retreats with celebrity mentors including Robbins, who has had many high-powered business clients over the last 30 years - like billionaire investor Paul Tudor Jones. Last year, Robbins approached Shopify with the idea of developing a similar contest for young companies that were further along in their development.

To enter, applicants had to have a business that sold product through Shopify's platform and had more than $1 million in annual sales. Applicants' growth was measured between March and July this year. Shopify said there were several thousand applicants across 70 countries. Average gross merchandise volume (product price multiplied by number sold) growth over the five months was 14% total, but over 500% for the top 10.

The company with the highest gross sales gain, Gymshark, and the company with the highest sales gain percentage, Skinnymixers, rang the bell at the New York Stock Exchange on Tuesday and will be receiving marketing packages and support from the firm Sid Lee. The panel of mentors selected the remaining six winners based on merit.

"The biggest surprise was how big they became," Shopify COO Harley Finkelstein told Business Insider. He said that one of the main benefits of Shopify's contests has been the lasting and fruitful networks that emerge each year.

Meet the winners below: