The video, released by Sony Music Tuesday, can be viewed on video-sharing website YouTube.
"Making of the Legend" showcases the training and physical work that the actor underwent to achieve an athletic body similar to what 'Flying Sikh' Milkha Singh, a former ace athlete, had during his championship days.
"Six months of training, four to five hours, over two sessions six days a week got me to be like this," Farhan said in a statement.
"Bhaag Milkha Bhaag", releasing Friday, is Sony Music's second project with director Rakeysh Omprakash Mehra. Composed by the leading musical trio Shankar-Ehsaan-Loy with lyrics by Prasoon Joshi, the music of the film was released in May.