Before Mint.com, I was a long-time user of 'Microsoft Money' and Intuit's 'Quicken.' Both were powerful tools, loaded with features and functionality around taxes, investment, budgeting - too feature-laden, in fact. They took hours to set up, forever to learn, and an hour a week to maintain.

The original idea before Mint was a life and goal planning system I called Carpe Viva. The idea was that all of life's goals, from buying a house, getting an MBA, or learning Spanish could be quantified in both time and money.

Carefully calculate the potential size of your market to make sure you can grow. Before starting Mint, I knew that there were about 20 million people who had purchased 'Quicken' or 'Microsoft Money' over the years, and 80 million people using online banking in the U.S. alone.

I always knew I wanted to be a technologist, so I went to Duke and got a degree in computer science and electrical engineering. Really, I thought my goal in life was to be an inventor, a problem solver, so I thought I needed a Ph.D. to be good at inventions, but it turns out that you don't.