However, on Feb 27, there was an unexpected break in the Big B's hunger-strike regime for Satyagraha when director Prakash Jha turned 61.
It happened at the sprawling Ramlila Ground in Bhopal, where Jha was shooting a mammoth public-rally scene with the Big B on a hunger strike.
A live musical band was also present for the shooting.
Suddenly all work stopped and everyone in the cast - the Big B, Ajay Devgn, Kareena Kapoor, Manoj Bajpayee and Arjun Rampal, burst into a live rendering of Happy Birthday for their director.
Recalling the magical moment, Jha said: "We were shooting a critical public sequence with the entire cast and a live band was also there, when suddenly everyone burst into Happy birthday to you for me. I hadn't told anyone it was my birthday."
"I am not a birthday person at all. I never celebrated my birthday even as a child. So on Wednesday, at first I was embarrassed, and then deeply moved. Not every day do you get Bachchan sahab to sing Happy Birthday with a live band."
Incidentally, in the film, the Big B plays an anti-corruption crusader very similar to Anna Hazare.