Airbnb books 1 million guests Memorial Day weekend. Here’s how they did it.

How do 2 poor college students in need of rent money launch an idea that investors initially ignored, and grow it into one of the world’s most successful industry disruptors? Airbnb originated when co-founder Brian Chesky was $150 short for a monthly rental payment of $1,150.

To close the gap, he decided to turn his house into a B&B for a weekend, when San Francisco was facing a hotel shortage due to a large conference. The only problem was that he didn’t have any beds to offer, so he offered air mattresses, and marketed his home as the Air Bed & Breakfast.

From that weekend in August 2008, it’s grown to where the company is today, which boasts 252,000 people booking an Airbnb room every night.

For the 2017 Memorial Day weekend, the company has 1 million bookings, which is twice the number of bookings from 2016.

Chesky shared 4 entrepreneurial lessons in an interview with DeZeen that all entrepreneurs can apply to their own businesses.

1: Ignore the Haters & Non-Believers.

When Chesky and his co-founder Joe Gebbia initially sought investors in Silicon Valley, they weren’t taken seriously. “One of the reasons was they thought the idea was crazy. People thought: ‘I’d never stay in a stranger’s home. That’s creepy’. But the other reason is that they didn’t think a designer could build and run a company. They were straight up about it,” explained Chesky.

However, through it all, the founders never gave up. In the end, their design mentality is what lead to Airbnb’s transformation from failing startup to billion-dollar company.

Getting an idea off the ground requires support, and rejection can be deflating, but successful entrepreneurs persevere. They learn how to shut off and shut down the people who don’t believe in them.

“More than anything, entrepreneurship is a game of attrition. It’s about having the determination, the discipline, and the cash to see it through. It’s about not giving up,” writes Steve Tobak, Entrepreneur columnist and author of Real Leaders Don’t Follow.