The entrepreneurs leading 8 of the fastest-growing new retailers in the world share their best business advice

Lavery and Brouwer are two New York-based entrepreneurs whose SELF Journal, a journal that guides its user through daily self-improvement exercises, raised $322,000 in about a month on Kickstarter in late 2015. The product helped them launch BestSelf Co., which brought in $2.4 million in sales last year, and which they expect to bring in $12 million this year.

Lavery and Brouwer were not only Build a Bigger Business winners, but were also winners of Shopify's Build a Business competition last year, an annual contest for startups. They said that both experiences taught them that "having the support of other business owners on the same level as you is invaluable," Brouwer said.

Building relationships with other entrepreneurs has allowed them to see that the problems they've run into are not unique, and that all entrepreneurs have different skill sets and accompanying insights to share.

It's about "being able to bounce ideas off of one another and figure out what's working, what's not, in each of our businesses and help each other level up," Brouwer said.

Griffiths launched Knixwear in 2013 on Kickstarter with a bra that could be worn both at work and at the gym. It raised $1.5 million, becoming the most successful fashion project in the crowdfunding site's history. The Toronto-based company has grown well past that initial product, and is expecting $20 million in sales this year, up from $5 million last year.

Griffiths said that her mentoring session with Robbins cemented an insight that came from all of the trip's mentors: There's no point obsessing over the notion of "impostor syndrome," since every successful person deals with the anxiety of maintaining success and building upon it.

"Every single one of these people experiences this because this is what happens when you push yourself, and you build, and you're constantly stretching outside of your comfort zone," Griffiths said. "Of course you're going to feel unsteady. And so ... this is part of the process. ... That has been a really liberating thing."

Vaccarino started Fanjoy in San Francisco in 2014 as a way to connect musicians with their fans through gift boxes, an offshoot of subscription boxes like ones offered by Birchbox.

He noticed the rise of YouTube celebrities was becoming a lucrative business, and decided to partner with some of the biggest stars, like Jake Paul. This evolved into Fanjoy becoming a company specifically for YouTube influencers and their fans. Since making this pivot in January, Fanjoy went from moving 5,000 units monthly to 120,000, which will result in the growth of annual sales from $1.2 million to $35-40 million.

As a first-time founder, Vaccarino said that he had difficulty dealing with the reality that he did not have to always be on friendly terms with all of his employees and clients. He said that Robbins helped him both recognize and begin to overcome this fear of confrontation.

"Tony gave a really good example of if you're a parent and you have a kid who's given everything, it's really hard to switch that to discipline and gaining respect from them after they have everything and there's nothing really there for them to work for," Vaccarino said. "But that tough love will, in the end, probably make you guys closer."

The Akersons are a husband-and-wife team who founded Kindred Bravely in 2015 based on Deeanne's personal need she knew other women must share.

Akerson wanted high-quality maternity clothes that moms could wear through pregnancy and then nursing, clothes that wouldn't be hideous, painfully uncomfortable, or both. The California-based founders said that because of increased focus and new product lines, Kindred Bravely's annual sales grew 12x from 2015 to 2016, and that they expect 2017's sales to be almost triple last year's.

Deeanne said that as her company began growing rapidly, she began feeling that she was neglecting her two young sons. She told us that during the Fiji trip, Robbins helped her realize that owning a successful business was linked to her happiness, but that running this business at what she felt was the expense of her family was having the opposite effect.

But Robbins also explained that there was solution: Hire a CEO. "That solidified in my mind that this is the direction that our company needs to go — not just for the success of it, for the level we want it to be — but also for my piece of mind too so that I'm not stressed to the max and on the edge, feeling like I'm missing out on important moments with my kids," Deeanne said.

Ford, Leibel, and their third cofounder, Bruno Aschidamini, were three friends living in San Diego who launched a line of fashionable, high quality beach towels in 2014. Sand Cloud now has a full line of towels and apparel where 10% of proceeds go to marine life conservation. Sand Cloud grew from $30,000 in sales its first year to $2.5 million in 2016, and are expecting to bring in $7 million this year.

Ford said that the best piece of advice they ever heard was, "If you're not growing, you're dying."

"If we're not growing, then we feel like we're on the brink of going out of business — even though we're not — but if we have that mentality, it just fuels us to work harder," he said.

He and his cofounders built that urgency into their company from day one, when they quit their jobs with essentially no safety nets. They had to work odd jobs and live off rice and beans during those early days, Ford told us. "We were just so desperate to make it work that we made it no other option," Leibel said.

The New York-based entrepreneur began working full time on Lively in 2015 and launched in April 2016. That October, she raised $4 million in a seed round led by GGV Capital, and is looking to do to the lingerie business what Warby Parker did with eyeglasses.

Cordeiro Grant won the title of "Tony Robbins' Pick," and in their one-on-one mentoring session Robbins told her, "I'm passionate, I'm intense — I relate to you. That's probably why I have an affinity for you, right?" But he also said that he knows this unrelenting, aggressive push to constantly work on moving a business forward can lead to burnout if it's not used properly.

Robbins told her that the passion she has for her business gives him no concern about her failing to continue to grow and enjoy success. But he wanted her to learn to temper this passion for the sake of her well-being, which will allow her business to be more sustainable and fulfilling. To do that, she must clearly iterate a plan and be confident in it, rather than constantly powering through uncertainty.

As Robbins said, "there's a power in that total calmness. There's a power when there's no stress whatsoever. And not even excitement, just absolute knowing."

At the end of the session, Cordeiro Grant said that as she continues to grow her business, she will take Robbins' advice and not live in a constant frenetic state. Instead, she'll learn from each win and failure "and elegantly move on to the next. With that, there's balance and focus."

Francis founded Gymshark in England in 2012 out of his garage as a fitness apparel brand built around a curated fitness community. It is the fastest-growing brand in the United Kingdom, as ranked by the Sunday Times Fast Track 100, and is on track for annual revenue this year of £41 million, an increase of 215% year over year.

Francis told us that he would fill his spare time online studying lessons from successful businesspeople and management experts, and a lesson that he kept noticing was that you must focus on what you're good at and pass on the rest.

It became obvious to him that he needed to hand over the CEO reins this past April to his experienced managing director Steve Hewitt, allowing him to be the brand visionary while Hewitt handled the day-to-day. As Gymshark has grown, he's had to share more responsibilities with others.

"Gymshark is my baby. So it is a bit of a weird feeling," he said. But "I know that this is the best way to grow the business and it is best not only for me but for the business as a whole."