Salman, 49, who will be donning a physically strong character for the film, said the film involves a lot of action scenes.
"I have to work a lot for this film. It is going to be a stressful film. In November, I start shooting for it. There is lot of action in it.. Wrestling types... Weights... Lot of muscles. I have to be very strong," Salman said in an interview.
"So it is not about body, it is not necessary that he will be ripped in six packs but he is very strong," he said.
Salman and producer Aditya Chopra have decided to release "Sultan" on Eid 2016. The film produced by Yash Raj Films will be directed by Ali Abbas Zafar.
Salman has often said that Hollywood action star Sylvester Stallone has always inspired him in his life.
On would you like to remake Stallone's "Rocky" series, the "Dabangg" star said, "No. I mean it has been made not once but so many times. Everyone has seen it. It will be very difficult to compete with what they have done."
Other actors who are donning the boxer gloves, are superstars Akshay Kumar and Aamir Khan.
While Akshay plays a boxer in Karan Malhotra's "Brothers", Aamir is getting ready to play a wrestler in Nitish Tiwari's "Dangal".
"It is a beautiful film (Dangal). He is playing a father of two in that film. I have no children in 'Sultan'.
Ours is a sports film but there is action, there is a love story. There is no negative force.. He just has opponents," Salman said.