The Rocket attributed his win to his gladiator spirit after coming from 3-0 down to beat David Gilbert 10-5 on Saturday.
The world number one is hunting a record-equalling seventh title and will now face Mark Allen or Scott Donaldson in the second round.
O'Sullivan reeled off six frames in a row to take control after Gilbert had raced into a 3-0 lead at the Crucible.
The six-time champion told the BBC: “I am out there playing, enjoying it and just trying to compete. It is like Gladiator. Russell Crowe has a hole in his arm and knows he is going to die, but you just have to find a way. That is what winners and gladiators do.
“I probably wasn't born to play snooker, but I was born to do something with a ball. I just wish it would have been another sport where my temperament would have been suited to it. I find snooker challenging.
"To be the best at something it takes graft, time and effort. Sometimes you ask yourself, 'Why am I doing this?'
“I was never born a winner, but I had to have it drummed into me. A bit like Serena Williams and Tiger Woods, I had that type of father figure where I was told, 'You are going to be a success'.
“I wasn't that bothered, but I was toughened up mentally. I was mentored that way.”
But O'Sullivan faces disciplinary action after he was caught on television making an X-rated gesture after missing a black ball during his win over Gilbert.
He missed a black off its spot during the 13th frame and replays appeared to show the six-time world champion making a lewd gesture as he made his way back to his seat.
World Snooker has confirmed that the incident has been referred to its disciplinary committee.
“We are aware of the incident and it has been referred to the World Professional Billiards and Snooker Association disciplinary committee,” World Snooker Tour’s head of media Ivan Hirschowitz told Eurosport.