The Munster and Ireland points machine was particularly harsh on himself as he assessed his opening game performance against the Royal XV, even though he notched a match winning 22 points and didn't miss a kick.
Having sat out the next two games, he finally gets his chance to link-up with Wales scrum half Mike Phillips against the Sharks in Durban tomorrow night.
"I felt like a robot and an imbecile on the pitch during the first game. I underestimated the effects of altitude," said O'Gara.
"The mind was telling me one thing, but the body wasn't getting into position to do it. We were sluggish and the boys took it up a fair few notches in the next game.
"By then we'd had eight days at altitude by then and everyone felt fresher. We were disappointed with the way the game went on Saturday and now we have another opportunity to make an impact.
"If we get it right at forward maybe we can express ourselves a bit more. It is all to play for."