Fundraising for a startup can seem like a full time job. From countless phone calls to meetings with skeptical investors, the necessary process of fundraising is painful at best. Need some inspiration to stay at it? Back in 2008 the three co-founders of Airbnb were on a mission to change the hospitality and travel industry. They knocked on the doors of dozens of investors but no one seemed to buy into their idea. Just 8 years later, Airbnb is not only going strong but worth a staggering $25B. Now Cofounder and CEO Brian Chesky is sharing rejection letters from investors who passed on Airbnb in 2008 and are no doubt kicking themselves now. These prove that perseverance and believing in your idea in the face of doubt is the key to your startup’s success. Read more here, and make sure to save those rejection emails!