Kara Goldin broke her Diet Coke habit by putting fruit in her water. It was the ‘aha’ moment that lost her 50 unwanted pounds and she’s now on target for $1bn unicorn status. Kara is founder and CEO of hint®, a healthy lifestyle brand that produces unsweetened water. Melinda Wittstock talks to Goldin about what inspires and frustrates her as a female entrepreneur, and why the biggest obstacle to success are the walls we build ourselves.