Chip and Joanna Gaines have built a multi-million-dollar design empire, but the HGTV stars said their road to success started on shaky ground.

The "Fixer Upper" stars, who are synonymous with Waco, Texas, shiplap and "demo day," revealed at Hubspots' annual "Inbound" event on Friday that they had concerns about their relationship.

"Every Friday, we were saying, 'Are we gonna make it?'" Joanna Gaines said of their early struggles before their rise to fame.

At one point, she added that they feared the worst personally and professionally.

"The four or five years before we did the show, when the housing crisis hit, things were so hard for us," Joanna Gaines said. "We kept pressing through, even in those hard times."

She continued, "The value of what we learned in that is something I'd never want to do again, but I'd never not want that. The hard is what makes us appreciate this."

Despite her unique and keen eye for design, Joanna Gaines said her passion didn't come easy.

"What I realized is I had to step out. I had to be curious. I had to become a learner. I had to learn that and with that came the passion," she explained.

The parents of five are still working to strike a balance, now with even more on their plate as they prepare to launch their new cable network with partner Discovery Inc., and they admitted that working so close isn't always easy.

"We definitely disagree. It's not perfect. But for Jo and I, it really is a special bond we're extremely proud of," Chip Gaines said. "We work really well together."

He also shared the "secret ingredient" that keeps their marriage so strong.

"Solid mutual respect," he said. "A lot of hard work goes into this, but if you can get to a mutual place of respect, you can change the world."