Director Raj Kumar Gupta, known for helming films like "Aamir", "No One Killed Jessica" and "Raid", says making films is a constant challenge, but his first project will always remain close to his heart. As his first film "Aamir" clocked 10 years since its release, Gupta said that the success of the movie inspired many filmmakers.

"Every film is challenging. With the kind of subjects that I have picked, each film was challenging for me. It will be very difficult to pick just one," Gupta told IANS over phone from Mumbai. "The constant struggle is to make a film. Your film is your calling card. In that sense, first film is always special. That is something people know you by because before that people didn't see your work. They know your talent and whether you are capable of doing it or not," he added.