Here is a passage from chapter two of ↑Glenn Greenwald‘s excellent newest book “No Place to Hide: Edward Snowden, the NSA, and the U.S. Surveillance State” (2014), which I’ve recently read:

Finally, Snowden gave me an answer that felt vibrant and real. “The true measurement of a person’s worth isn’t what they say they believe in, but what they do in defense of those beliefs,” he said. “If you’re not acting on your beliefs, then they probably aren’t real.”
    How had he developed this measure for assessing his worth? Where did he derive this belief that he could only be acting morally if he was willing to sacrifice his own interests for the sake of the greater good?
    “From a lot of different places, a lot of experiences,” Snowden said. He had grown up reading large amounts of Greek mythology and was influenced by Joseph Campbell’s The Hero with a Thousand Faces, which, he noted, “finds common threads among the stories we all share.” The primary lesson he took away from that the book was that “it is we who infuse life with meaning through our actions and the stories we create with them.” People are only that which their actions define them as being. “I don’t want to be a person who remains afraid to act in defense of my principles.”
    This theme, this moral construct for evaluating one’s identity and worth, was one he repeatedly encountered on his intellectual path, including, he explained with a hint of embarrassment, from video games. The lesson Snowden had learned from immersion in video games, he said, was that just one person, even the most powerless, can confront great injustice. “The protagonist is often an ordinary person, who finds himself faced with grave injustices from powerful forces and has the choice to flee in fear or to fight for his beliefs. And history also shows that seemingly ordinary people who are sufficiently resolute about justice can triumph over the most formidable adversaries.”
    He wasn’t the first person I’d heard claiming video games had been instrumental in shaping their worldview. Years earlier, I might have scoffed, but I’d come to accept that, for Snowden’s generation, they played no less serious a role in molding political consciousness, moral reasoning, and an understanding of one’s place in the world than literature, television, and film. They, too, often present complex moral dilemmas and provoke contemplation, especially for people beginning to question what they’ve been taught. (Greenwald 2014: chpt. 2)