When I graduated from college in 2005, I decided to go into the game industry and ended up at my dream job as a software engineer at Nintendo outside of Seattle. I loved it there -- I was working for a company that I loved, and the work was rewarding and interesting.
A few years later, I left the company to work on some solo projects in the game industry. It was about this time that I picked up a copy of Carl Sagan's Cosmos, almost on a whim, as leisure reading for a plane ride. I instantly found myself transfixed by its message, and my jaw literally dropped as I realized that I wanted to do something different with my life: to promote the cause of human exploration of space.
From that point on, I worked toward this goal, even though my experience up to that point had been in video games, and I had no aerospace background whatsoever. I got guidance from a number of mentors in the industry: Neil deGrasse Tyson at the American Museum of Natural History, Piet Hut at the Princeton Institute for Advanced Study, former astronaut Rusty Schweickart, and Tara Estlin here at JPL, among others.
I returned to Nintendo and kept working as a software engineer, but took night classes to get a masters degree in computer science and studied astronautics, astronomy, and mechanical engineering on the side. Eventually, I enrolled in the University of Washington's Masters of Aeronautics and Astronautics program, and I quit my job to become a full-time student and wholly dedicate myself to space exploration.
When I quit my job, I saved this screenshot from my "exit survey":