Anand was based on my relationship with Raj Kapoor, I wrote it when he wasn’t well: Hrishikesh Mukherjee 

Filmmaker Hrishikesh Mukherjee made many popular movies in his day but the film he is most remembered for is his 1971 film Anand, which told the story of a dying man who spreads cheer wherever he goes. Starring Rajesh Khanna in the titular role, the film had him sharing screen space with a then newbie Amitabh Bachchan. As Khanna’s character battled his ailment, Bachchan becomes his support system and is completely transformed with his undying positivity. A heart-wrenching story on screen, the film was, in fact, inspired the events of Mukherjee’s own life.
Mukherjee shared in a 1998 interview that this was a biographical film that was based on his relationship with filmmaker-actor Raj Kapoor. He told Rediff that he got the idea for the film after he became friends with Raj. “In Anand, one was a Bengali and one was a Punjabi. So it was clear what they had to look like. I got the idea to make this film after I became friends with Raj Kapoor,” he had said. In the film, Rajesh played the Punjabi character and Amitabh played the Bengali character.
Mukherjee said that he wrote the film when Kapoor was “suffering from a pulse problem.” Calling the film “a kind of a biography”, he said, “I wrote Anand when Raj Kapoor was not well. He was suffering from a pulse problem, but he still managed to smile and spread happiness around. I used to think if something happens to him, what will happen to me? We all were worried about him and he would be smiling always. The same way Amitabh would worry and Rajesh would brush it off.”

In the same interview, Mukherjee said that while the film is called Anand, after Rajesh Khanna’s character, he saw Amitabh Bachchan’s Bhaskar Banerjee as the main character. “He was the main character because he is there throughout the film and through him, we get to know the story. Rajesh Khanna was the second main character. I just had to look at Amitabh to know that he was right for the role,” he said.
Hrishikesh Mukherjee and Raj Kapoor had a long-standing friendship as Kapoor had worked with him in his second directorial, the 1959 film Anari. Mukherjee had once shared in a Filmfare interview that they first became friends when he traveled with the star to Moscow.
Mukherjee passed away in 2006 in Mumbai.