Aamir Khan, who has played a variety of roles in his 25-year-old career, says Dhoom 3 is his toughest role so far. In the last couple of years, the 48-year-old star gave hits in the form of Taare Zameen Par, Ghajini and 3 Idiots and his role in each of them was as different as chalk to cheese. But he said: "I think Dhoom 3 is my toughest role so far. I have never played anything like this before." Courtesy: Reuters Courtesy: Reuters "Every film is challenging, but this was a tough role. I had a great time working in the film," Aamir told reporters on Wednesday at the trailer launch of the film. In terms of preparation, the actor had to workout a lot for Dhoom 3. "I am playing a gymnast in the film. I also went for circus training for the film. There was a lot of hard work for the film. I followed a strict diet." The actor plays a negative role in director Vijay Krishna Acharya's sleek and stylish thriller — but says not to compare it with the typical villain of the big screen. "I liked  Show less