The 29-year-old actor is currently working on Vishal Bhardwaj's Matru Ki Biljee Ka Mandola.
He told IANS: "The biggest critics in my life are my mum and my wife Avantika.
"The truth is that when you become an actor, when you become a celebrity, people will come and tell you 'Bro, you are the best, you have done a good job'. So those people are everywhere.
"What is very rare is people who will say these are your weaknesses, this is your problem and this is where you have to work on. People who will honestly do that, those are very rare."
Khan added: "I never realised it before, but now I realise that you get tremendous benefit as an actor. Earlier, I have worked with first-time directors or second-time directors - there is a sense of two of us finding our way together. We used to find the correct way of working.
"Here I am working [with Bhardwaj] who has consistently proved himself and he knows what the correct way of working is."
He admitted in October that he had almost dropped out of the film because of the pressure.
The star was given five hours' coaching in the Haryanvi language so he can play a country boy.
Watch Khan in the trailer for Matru Ki Biljee Ka Mandola below: