The 33-year-old, who signed for Aston Villa under Martin O’Neill’s tenure in 2006, has made 186 appearances for the club, taking the armband after being voted the club's Player of the Year in the 2008-09 season.
Having been diagnosed with acute leukaemia in March 2012 and undergone chemotherapy treatment, Petrov is now in remission, and able to play a bigger part at the club's Bodymoore Heath training ground.
"First and foremost it's great that he's in remission and as he said, he's going to try and live a normal life," Lambert told reporters.
"I don't think anyone could envisage what he’s been through, unless they have themselves. It puts everything in perspective.
"I've known him since he was 19 when I first played with him and never in a million years did I think anything like that would happen to him, he's such a fit lad."
Just 24 hours after his diagnosis, Petrov visited Villa Park for his side's Premier League encounter with Chelsea, and received a standing ovation from the crowd in the 19th minute. The tribute caught the imagination of many Villa fans, who now perform repeat ovations at every game.
Lambert added: "The 19th minute of applause at the games is fantastic, from home and away fans. Thankfully, he's doing great. He did a little bit of work with the fitness guys the other day. It's great that he's on the road.
"When he comes into the building I'm pretty sure everyone will have a thought in their head, thinking 'my God, he’s done that' about what he's been through. You wouldn’t be human otherwise.
"It puts things into perspective and the lads love to see him, which is nice."
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