Hint Water CEO Kara Goldin's Most Important Factor for Success: RelentlessnessThe founder achieved her success by changing the beverage industry. Now she's trying to change Washington's approach to clean water.

When someone tells Kara Goldin why she can't do something, she replies in the same way: "Whatcanwe do?" After all,somethinghas to be possible! That attitude helped her turn her life around, and it led her to create the popular beverage brandHint Water. As she writes in her new book,Undaunted: Overcoming Doubts and Doubters,the journey began after she left her job at AOL in 2001 and tried to improve her health. She struggled to kick a diet soda addiction, couldn't find anything unsweetened in the marketplace that she liked, and set about building a lightly flavored, sugar-free water. Despite many manufacturing and retail challenges, she succeeded — and now, like in this conversation, she urges otherentrepreneursto approach their challenges "undaunted."

In your book, you write about a hard conversation you had with your husband in Hint Water's early days. You write, "We had no manufacturing partner. We were running out of inventory. We were burning through money. We had four kids at home, in a house in the most expensive city in the country. What the hell were we doing?" Many entrepreneurs ask themselves that question. What got you through it?