How did Aamir come to star in 3 Idiots? Rajkumar Hirani reveals, in the first part of a three-part exclusive interview with Moneylife. 

Moneylife: How did the casting of Aamir Khan happen?
Rajkumar Hirani: It was quite by chance. Frankly, I hadn't thought about Aamir. His last film was Fanaa and he was not looking young and was not on the radar for this one at all. Vinod had called him for another film, which he thought Aamir should do. So Aamir told him that you are calling me for various scripts, why aren't you offering me Raju's script? Vinod said that you don’t fit the role, but you can hear it if you want to. He called me and said Aamir is coming home, why don’t you come and narrate the script to him. I said, but he is not right for the role.
So Vinod said, why not narrate it to him, he is an intelligent guy and will probably have some observations that will help. So I went to Vinod's house and when I saw him, he was looking very good. He had just done Ghajini and had built up his body. He was looking big, but his face was looking much younger than it was in Fanaa. He heard the script. He had some issues with it, but we had a chat. He said, 'what do you think? Am I right for the role?' I said, I don't know but, at the moment, you are looking very good. He said, ‘I can look younger than this. I will completely lose my muscles and can look younger, but the problem is how will I feel young and get the mannerisms of the youth right’? I hadn't finalised the script until then, so I said, ‘I need another three months. I will narrate the script to you again and, if you still like it, then we will work on it. So after that, Abhijat and I went to Pune and worked on the script. We narrated the script to him just when his Taare Zamin Par was releasing. He is also like Boman, completely emotional and was crying when he heard some scenes. It used to be a joke. Every time I narrated these two scenes when Sharman (Sharman Joshi) goes to give the interview and Maddy (Madhavan) goes to tell his father that he doesn't want to do engineering and he would get all emotional and sob like a baby.

(For the complete the interview, please pick up the next issue of Moneylife to hit the stands on Friday)