Tony Robbins argues that hunger is the most important indicator of success. Self-made real estate tycoon Sean Conlon explains that his own hunger comes from his modest upbringing and immigrant story.

Growing up, Conlon's family of seven lived in a 1,000-square-foot home in a small Irish village of about 900 people. When his parents struggled financially, the bank threatened to take their home. "That was ingrained in me," says Conlon.

"I swore then that that would never happen to me or to anyone I cared about."

When Conlon moved to America at the age of 18 with $500 in his pocket, he was motivated by his fear of once more facing the same poverty he faced as a child: "I was driven by being afraid of the bank knocking on the door like they did with my parents."

America, Conlon explains, was the place he came to fight his fear: "America is a place where you can still be anything today … I am very proud to be an American citizen." He arrived in Chicago in 1990 determined to make good.

Conlon got to the top by being more dedicated than his colleagues, he says: "I outworked all my competitors." That work ethic gave him an edge. "I competed with guys who went to the Ivy League schools and they went to Harvard and Yale and Wharton," he says, "but they wanted to go home earlier in the evening."

When they went home, Conlon kept at it. "I got an extra day's work done that night, so I was a day ahead of them the next week and two days the following week," he says.

The real estate mogul argues that this fear-based passion is special to entrepreneurs who have experienced difficulty: "I think a lot of people you will talk to who immigrated or came from, as they say, the other side of the tracks, are driven by fear."

On the flip side, explains Conlon, privilege can often cause entrepreneurs to take things for granted. "Sometimes people who are born here feel they should be entitled" to opportunity and success, whereas "I didn't feel I was entitled to anything except the shot," he explains.

Despite being a self-proclaimed "chilled" and "pragmatic" person, the fear of being poor still sparks terror in Conlon: "If somebody tries to screw me over, I think back to all the people who screwed my father out of money, and I react very viscerally to it because I am afraid of being poor still."

No matter how much success Conlon manages to achieve, fear continues to drive him: "I am still afraid no matter how confident I seem." His story is a great reminder to work hard, harness your fears to fuel your passions, count your blessings and take nothing for granted. "America is an amazing place," says Conlon "We're very fortunate to be here."