Serial entrepreneur and CEO of VaynerMedia, Gary Vaynerchuk, is kicking off the new year plotting another expected sell-out sneaker collaboration.

Last year he partnered with K-Swiss to release the first collection of sneakers inspired by the entrepreneurial lifestyle. While you'll have a hard time getting your hands on a pair of the original GaryVee 001 or 002 (they sold out within hours of launching on the media mogul's 42nd birthday), Gary and K-Swiss President Barney Waters have shared teasers on Twitter of the upcoming GaryVee 003 and 004 release. It sounds like round two may be even more exclusive and, gauging from the first limited production run, even harder to snag.

I recently had the chance to talk with Vaynerchuk about the collaboration during an energetic, five-minute phone call. A true master of efficiency, Vaynerchuk called in for what I imagine was one of many brief calls, all while getting in his daily walk. You can listen to our entire call here.

He shared insights from what he calls his breakout year, what's on the horizon for future K-Swiss collaborations, and his top advice for anyone looking to create a profitable side hustle. I took four main lessons from our five minutes chatting:

1. Don't outsource confidence.

No one has ever made sneakers specifically aimed at the "entrepreneur lifestyle," but that didn't stop Vaynerchuk from diving in. "I really thought it was going to go well. I felt really confident going in," he said.

But even with his previous success and accomplishments, people still underestimated Vaynerchuk. "You know what actually surprised me the most?" he told me. "Is how many people, that were close to me, still underestimated me."

The lesson? You can run a multi-million dollar business, employ a team of hundreds, and yet, there will be people who still underestimate you. Don't count on others to give you validation when launching something new.

This is a lesson I've learned first-hand many times when launching my own business and pursuing projects or ideas that push the boundaries of what is traditionally viewed as possible, safe, or accepted. Believe in yourself and do it despite the naysayers.

2. Seek passion over profit.

Side hustles take work, but it shouldn't feel like work. Whether you're looking to sell a product or provide a service, it has to be something you're passionate about.

"Do not go after sneakers or slime or iPhone cases because that's where the money is," Vaynerchuk said. "Sell something around an elf costume or Smurfs or Captain Crunch cereal because you love it."

I was recently tempted to do the opposite when launching an e-commerce shop -- but, I resisted the temptation to sell the trending products (you've seen the ads, from charcoal face masks to weird snow scrappers). Instead, I focused on an area I already know and enjoy as a mom: modern and affordable baby clothes. It's made the challenges of learning and launching a new business feel more like a hobby.

"If you're going to work from 8 p.m. to four in the morning, it might as well be the same thing you would have watched a movie about or played a game... soccer, or whatever," Vaynerchuk said. "Your side hustle has to be completely tied to your passion or otherwise you won't have the energy to succeed.

3. Be strategic.

Passion is key, but so is strategy. Vaynerchuk grew up with the buying-selling-flipping mentality, so it's no surprise his K-Swiss launch had the perfect combination of scarcity and demand to drive sales and create opportunity.

Within days, the sneakers were listed for upwards of five-times the retail price on eBay and other resale sites. As a smart, savvy marketer, he knows the power of testing, analyzing and optimizing.

"I thought there would be a chance for a sellers market," Vaynerchuk said. "I felt the pulse of it. I felt there was a fan-base there that would get involved... it's surprising how cultural sneakers are."

He added, "I've always been good about consumer behavior. I know where the world's going. It's discipline."

4. Stay humble.

But for Vaynerchuk and other high-performing entrepreneurs, it's not about being bullish at all costs -- it's entirely the opposite. They understand concentrated focus and staying humble is key to success.

"It's the humility part that allows me to be strategic, which is what got me there."

This may be the biggest lesson of all. If you focus on the first 3 tips, you should find some amount of success. Taking time for gratitude and recognizing the people and the process that got you there, will ensure the success lasts.