Amit, 32, said in the film his character goes through a transition from a young adult to an aged man.
"It was a challenging role to play. The character starts from 25 and goes through till he turns 50-year-old. I had to gain and lose weight to don the transition in my role. My director Tigmanshu Dhulia helped me a lot to understand the role. He is a great director and is known for making people act," Amit told PTI.
The actor, who recently wrapped up the shooting of the film, said 'Yaara' is a period drama that travels to the time period of 1975 to the current day.
"I have finished my leg of shooting schedule. It's a gangster film in the backdrop of friendship. It is also a period drama, which starts from 1975 and transcends into today's time," she said.
The film stars Vidyut Jamwal and Shruti Haasan in pivotal roles besides the 'Kai Po Che' actor.
Apart from 'Yaara', Amit will be next seen in Shoojit Sircar's "Runningshaadi.com" opposite Taapsee Pannu.
In the love story, he plays a Bihari boy who works hard to make his ends meet in Punjab.
"The film is a story about a boy and girl. It is set in Punjab. I play a Bihari guy, who stays in Punjab and manages his living by working in a garment store. He eventually falls in love with the daughter of the owner. He launches a marriage website too to help people to get married," he said.
Amit, who is making a comeback to the big screen after a gap of two years, said he has never planned his career. Asked if it is a conscious decision to do different roles, Amit said, "I have never planned my career. I feel an artist is much different from a lawyer and accountant, who can calculate their next step. I simply get up every day and thank God for giving me whatever I have in my life," he said.