The England midfielder was sidelined by a hernia and groin problem for four months late last year and has only just returned to action. The injury was far worse than at first thought and he is still in some discomfort.
"I've got to try to keep it strong because I've got a weakness there," Lampard said. "My tendon came off the bone and it doesn't go back, you just have to stay very strong in that area.
"I've spoken to players who've had it and they know the frustrations and the aftermath and what you have to do. It's no problem - you just have to do an extra two or three sessions a week in the gym to keep it strong.
"There are no sharp pains or anything, but the more games I play, the sharper I'll be, and I'm determined to have a good second half to the season because I basically missed the first half."
Lampard's absence saw an alarming slump in form from reigning champions Chelsea, who are now in fifth place, nine points behind leaders Manchester United and having played one game more.
It was their worst run in the league for almost 15 years.
Lampard, who helped lift some of the gloom at Stamford Bridge on Sunday with a double in the Blues' 7-0 FA Cup thrashing of Ipswich, said: "There's a bit of a gap. We can't afford to look around too much. We just need to win game by game. That's the position we're in now.
"We were up there early in the season, playing some great stuff, but now we're not."
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