In the Scot's debut campaign in charge, Villa were involved in a relegation battle for most of the year before they went on to finish 15th in the Premier League, five points clear of the bottom three.
Lambert has confessed that Lerner, like many foreign benefactors in the English game, may have been tempted to sack him, but has applauded the American for not pressing the panic button.
"I remember Randy saying to me, 'Paul this will be your hardest year in football' and he was right. It was tough, really hard," Lambert told The Sun.
"But we stuck to our beliefs and the crowd were great, even though we were getting beaten - sometimes pretty heavily. The supporters could have turned on me but they were excellent.
"Some owners would have got rid of me, I know that. They would have panicked and gone, 'Boom, you're out. Thankfully, I have had a good relationship with Randy and Paul Faulkner, the chief executive."
Villa host Tottenham Hotspur in the Premier League this afternoon.