Editor's note: Watch the interview with Conan O'Brien on Monday night. "Piers Morgan Tonight" airs at 9 ET weeknights on CNN.
(CNN) -- "I've always only been interested in trying to make people laugh," Conan O'Brien told Piers Morgan, "and trying to be funny and make things that would have made me laugh, you know? Or my brothers laugh, or my sisters laugh, or my parents laugh. That's always been the motivation for me."
The host of TBS's (sister station to CNN) "Conan" is a guest on tonight's "Piers Morgan Tonight."
"It starts with the family," O'Brien told the CNN host. "I'm from a large Irish-Catholic family and trying, the benchmark, for me, is trying to make my dad laugh or trying to make my brothers laugh at the table when we were having meals together."
The third of six children, O'Brien and his two older brothers, one younger brother and two younger sisters grew up in the Boston suburb of Brookline, Massachusetts.
O'Brien, 49, who began doing Charlie Chaplin impersonations in the third grade, recalled wanting to take tap dance lessons as a child in the 1970s.
"I grew up on old movies," explained O'Brien, who said he loved gangster movies and the films of Humphrey Bogart. When "That's Entertainment" was released in 1974, the young O'Brien was convinced he had to know how to tap dance in order to make it in show business.
"It's showing you what entertainment is," recalled O'Brien. "I thought, like an idiot in the 1970s, that that was what entertainers needed to have to know. You have to be like Donald O'Connor or Gene Kelly. You've got to know how to sing, dance, move. You've got to know how to do it all."
O'Brien said that his mother, a lawyer, and his father, a microbiologist, thought he was bluffing, but encouraged him to follow his dream nonetheless.
"They found me this really old African-American gentleman," said O'Brien, "who had been the protégé of Bill "Bojangles" Robinson. And he... worked out of this dilapidated studio and taught all these... people how to dance. I was the only white kid there... Not only that, I was tiny and I had bright orange hair... So all these beautiful black women are learning jazz, tap and all this kind of stuff and then I would march in with my box of tiny shoes..."
When Morgan pointed out that O'Brien doesn't possess the "agony" and the "torment" that plagues a lot of successful comics, the "Conan" host admitted that he has always grappled with insecurity.
"I was always a very hard-working student and wanted to go to a good school and worked really hard to go to a good school," said O'Brien, who attended Harvard University. "And then when I got there, I immediately had the fear that a lot of people have, which is, I don't belong here. These other people know a lot more than I do. They're smarter. I'm the fake. I'm the phony. And I think that is the common denominator that you see with a lot of people, whether they're artists or performers. They don't think that they belong."
Getting into comedy, O'Brien said, "was a very beautiful accident, because I worked very hard at everything and I tried really hard. Comedy was something that I stumbled into when I was in college."
O'Brien soon began writing for the college humor magazine.
"It was like falling off a log and discovering what it is that I was meant to do," he said. "I loved it. I absolutely loved it."
After Harvard, O'Brien moved to Los Angeles and landed a sketch comedy writing gig with the then-fledgling Fox Network. The show he was writing for flopped, but O'Brien was hired shortly thereafter as a writer for "Saturday Night Live." After "SNL," Conan struck out on his own and wrote an original sitcom. The pilot fared terribly in the ratings. O'Brien then wrote for "The Simpsons" before being selected to take over David Letterman's spot at NBC's "Late Night" in 1993.
O'Brien's string of successes and failures were the basis of his 2000 Harvard commencement address.
"I've looked good, I've looked bad, I've been praised, I've been criticized," his speech read, "but my mistakes have been necessary. I've dwelled on my failure today, because as a graduate of Harvard, your biggest liability is your need to succeed, your need to always find yourself on the sweet side of the bell curve. Success is a lot like a bright white tuxedo. You feel terrific when you get it, but then you're desperately afraid of getting it dirty, of spoiling it."
Back in 2004, O'Brien had negotiated a contract with NBC to take over "The Tonight Show" from Jay Leno in 2009. "The Tonight Show with Conan O'Brien" debuted on June 1, 2009.
But in January 2010, NBC announced that Leno would begin hosting "The Jay Leno Show" at 11:35 p.m., thus pushing "The Tonight Show's" start time to 12:05 a.m.
Unhappy with this plan, O'Brien struck a deal with NBC that permitted him to leave "The Tonight Show," which Leno again took over. This freed O'Brien up to negotiate with other networks, and he went to TBS. "Conan" debuted on November 8, 2010 and airs weeknights at 11.
"I'm honestly happier now... this feels... like a greater achievement... because I'm doing exactly the show I want to do. I'm doing it with people that I love. And we get to do it our way, and we're with these amazing partners at Turner."
O'Brien and Leno have not spoken since the "Tonight Show" fallout.
"I just think life throws you a lot of curveballs," said O'Brien, "and this is something that I didn't agree with, and I thought it was pretty screwed up, but we, everyone went through it. There was this sort of collective feeling about what happened. And then you move on from it."
Watch Piers Morgan Live weeknights 9 p.m. ET. For the latest from Piers Morgan click here.