When the B£4million summer arrival from FC Nordsjaelland went down in the Barclays Premier League defeat to Newcastle earlier this month he hoped his knee injury would only keep him out for a couple of weeks.
Instead the defender was told he had ruptured his cruciate ligaments, bringing a swift end to his debut campaign.
It was news the 21-year-old Denmark international found it difficult to deal with.
"I was really down and sad the first couple of days," Okore told the Birmingham Mail.
"At the beginning I just thought it was a minor injury and that I would be out for a couple of weeks.
"It was really a big blow when I was told about the serious injury."
Okore is due to undergo surgery on Wednesday before beginning the lengthy rehabilitation process.
And he is determined to get back to top form.
"I will fight to come back in the same shape as before," he said.
"I have never had this kind of injury before, so it will strengthen me mentally, but I would gladly have avoided this situation."
But Lambert has told Okore not to worry about events on the pitch just now and concentrate on his own recovery.
"The manager told me he was happy with my start in the club and that shouldn't worry about anything and just focus on getting back," he said.
- Disease & Medical Conditions