Lambert told reporters: "There's no point in looking back and thinking 'we should have got points here and there'.
"We lost two-goal leads against Manchester United, West Brom and Everton. It's tough when that happens because those points could have made a major difference. But it's happened and you just have to keep going.
"From now on in it's 12 cup finals and that's the way we have to view it. We have to be ready for it and win more times than not."
Next up for Villa is a trip to Arsenal on Saturday.