I'm at an incredibly interesting point in my life. I've built multiple businesses from the ground up, starting in the late '90s with one of the first e-commerce platforms for wine. That helped me grow my family's business from $3 million to $60 million in sales in less than five years. I'm an author, an investor, and a speaker, and I run one of the fastest-growing full-service media agencies in the world. Under my holdings company, VaynerX, I own Vayner­Media and PureWow and additional businesses, including my sports agency, VaynerSports, all while managing and growing my personal brand.

So call me a serial entrepreneur. If you want to start multiple businesses, here's something to keep in mind: You have to be self-aware. The problem with chasing multiple ideas without having a concrete base is that you get stretched thin. You don't see things all the way through. You become half-in across five businesses instead of all in on one, which would have been more successful.

A metaphor I constantly return to is "You have to have the steak before you can have the sides." I wouldn't be partnering to release my own sneaker or building a sports agency or thinking about acquiring or launching other publishing companies if I didn't have VaynerMedia as a base. Having a successful foundation allows me to do more. A lot of people, when they reach this level, start having other wants and needs, whether it's sailing or buying a third home or meditating. Me, I'm hungry to build. Can't help it.

From the outside, it may not seem like all of my endeavors connect. But if you look closer, you'll see I'm always trying to hack culture by studying consumer activity and understanding where, why, and how people buy and sell. I always try to remain relevant, and gather as much information as possible to then move into new things.

At this point, I believe I understand the fundamental aspects of launching a business well enough that I could launch anything. If you already own one company and are looking to start another, you have to first master these fundamentals: a great team, customer service, sales, and marketing. But you should start a business only if you believe in it. So many people sell products and services they don't believe in and ultimately come up short. How can you expect to labor day in and day out for something you personally hate? It just won't work.

My serial entrepreneurship is largely a product of observing and reacting. More than a decade ago, I saw that social media was going to be the zeitgeist for human connection--a new way to storytell and build relationships. That's why I started VaynerMedia, as a reaction to that reality and an insight into the market. It's the same way Snapchat became huge. Evan Spiegel and Bobby Murphy observed that individuals like selfies, and they created a service around that idea. They reacted to a consumer phenomenon, and built their product into the established vertical of communication. Any entrepreneur can and should do this.

I have a macro vision of "build more." Build as much as I possibly can. Build, get bigger, bigger, bigger, and eventually have more opportunities to leverage, leverage, leverage. At the most micro, I'm never fully romantic or all in on anything. Everything is being audited every day. I'm very comfortable with the notion that, even though I built VaynerMedia as a communications company, if tomorrow I see an incredible opportunity in seashells or cryptocurrency, I won't hesitate to change my mind. I will react to it, as any good entrepreneur should.

So, keep everything on notice, especially your assumptions.