People have rubbed their eyes in disbelief upon seeing Farhan Akhtar actually become the much feted Indian athlete Milkha Singh for the Rakeysh Omprakash Mehra film 'Bhaag Milkha Bhaag'. However, the transformation wasn't easy. It was definitely a challenge, but it was a challenge that was a very exciting one to accept, Farhan Akhtar says about his role.