"The number one thing is consistency," Mishler told CNBC Make It in London. "If you want to be a teacher (for instance), you can't sub out; you need to show up. And it's not just in the digital space — for anything, any practice, any service."

" Yoga With Adriene " host Adriene Mishler, who has accumulated 4 million subscribers and produced over 400 videos on YouTube, reveals her top two tips to cultivate a strong following — whether online or off.

Six years in the making and "Yoga With Adriene" (YWA) is one of the top-ranking brands on Google and YouTube for yoga tutorials.

At the end of the day, "it's a commitment," Mishler explained. While millions may follow the YouTube channel now, in the initial years, Mishler and her producer Chris Sharpe would get excited when a video received just 100 views.

"I was like: '100 views! Oh my gosh, this is amazing. A hundred people are doing yoga. This is amazing, let's keep going,'" she said.

Now, the videos tend to get hundreds of thousands of views, and the channel's most popular tutorial — a 20-minute video for complete beginners — has received over 18 million views to date.

Of course, it's hard to keep going, Mishler explained. "You have to show up when you don't want to. You have to show up when you have a big pimple on your face. You have to show up when you're in the middle of a breakup or a loss, and you have to show up even when the light is bad."

"I can think of a million things over the years where I didn't want to show up for the 'Yoga With Adriene' videos," she continued, "but I've never missed a week of the year, except for two times. And those were the two times that I had vocal surgery. And even then, we did a little series of silent ones."

"I don't say that to say, 'We're so amazing.' I say it because it's hard. It's probably the most challenging thing."