Anurag has told Kunal to build his physique 50 times much than what he currently is, and he has to do it in a limited time. Kunal had already been training himself, but since it was not possible within a limited time Kunal it seems approached his Rang De Basanti co-star Aamir Khan to help him out.
Sources inform that, "Ever since Aamir Khan developed his physique for Ghajini in a quick time, it has impressed Kunal so much that he has been taking special tips from Aamir Khan for the role.
He is also seen working out at Aamir's personal gym too. Kunal's character is supposed to look very strong physically since he is playing a desi superhero kind of character.
The film also requires him to learn certain skills; one such is "Paco' also known as free running. Paco helps in building stamina and agility."
Doga is the alter-ego of an orphan, Suraj whom Daku Halkan Singh finds in a garbage dump as an infant. He is brought up by Daku Halkan Singh, but treated like a dog.
While in Halkan's care, Suraj witnesses endless horrors that ultimately led to his becoming Doga. To seek revenge, Suraj becomes Doga, and wears a dog mask to hide his identity.
He is also considered to be the second most popular character created by Raj comics due to his huge fan following after Nagraj.
Kapoor loves to experiment onscreen and this role he says, is one of the most exciting and exhilarating experiences he has encountered.