Ponting, who played in 168 Test matches for Australia, said he stayed on because he wanted to help the next generation of Australian Test stars to come through.
"I probably played two years longer than I should have done," he told Sky Sports.
"I think I knew in myself that I couldn't get better. I felt that if anything, I could maintain a certain level. I think from 120, 130 Tests I knew I could not get any better," the batting legend said candidly.
"I wasn't playing for me, I was playing for the younger guys in the team. Great teams that I played in had a really good solid core of experienced players and great characters," said the two-time World Cup-winning captain.
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"I might be patting myself on the back here, but I thought I was one of those players," he said.
Ponting gave up captaincy after the 2011 World Cup and then played under Michael Clarke.
He suffered from a dip in form the last few years of his career and continued playing Test cricket despite being axed from Australia's one-day squad.