The "Badlapur" actor took to photo-sharing website Instagram to share the video where he was seen sporting just a pair of shorts.
Varun was sitting on a machine, and was working out for abs.
The 28-year-old captioned the video: "#tbt #abcd2 work out. Train drain @prashantsixpack @robodysculptor. #chunar 6am workout".
Directed by Remo D'Souza "ABCD 2" is a sequel to the 2013 dance-based 3D film "ABCD - AnyBody Can Dance". The film also features Shraddha Kapoor, choreographer-director Prabhudheva and international dancer Lauren Gottlieb. It is slated to release on June 19.