The England international, 32, returned in mid-December after missing more than three and a half months of the season.
"It was a bad injury. I was expecting it to be a few weeks and then I went to see someone who told me it was a three-month injury," said Lampard who was initially hurt in training while recovering from a hernia operation.
"It wasn't mis-diagnosed, it was more my fault. With hindsight I would have done a lot more resting when I first did the injury but I was trying to push to be fit when really I just had to wait for my body to naturally heal," he told the club's website
Lampard said he would need to put in extra leg strengthening work for the rest of his career in order to stay match fit.
"I will try to keep that (left) leg strong because I have a weakness there. My tendon came off the bone and it doesn't go back, you just have to stay very strong in the area.
"I know other players who have had the same problem; they know the frustrations of it, the aftermath and what you have to do, which has helped.
"It's not a problem, you just have to do an extra two or three sessions in the gym every week to keep it strong."
A fully fit Lampard, who has started Chelsea's last four Premier League games and scored twice in the 7-0 FA Cup demolition of Ipswich Town on Sunday, is a major boost to under-fire Stamford Bridge coach Carlo Ancelotti.
The London side's hopes of retaining the title appear forlorn having suffered five defeats in the last 11 league matches, a run that has seen them slump from top to fifth, nine points behind leaders Manchester United.
