Washington : Cristiano Ronaldo seems to make his son as fit as him, as he shared a workout video of him, teaching his 4-year-old son how to do crunches. The Real Madrid star shared the video, wherein his son Cristiano Ronaldo Jr. attempts to hold down his dad’s feet as the footballer fires off a round of sit-ups, E! Online reported. The 30-year-old footie ace told his son in the video to do at least 10 crunches to which Ronaldo Jr. followed obediently and after completing it the football star hoisted his son in the air, and complemented him as a champion while hugging him tight. In addition to this, professional athletes like Derrick Rose, PGA player Bubba Watson, Chris Paul, Ryan Fitzpatrick and Blake Griffin also brought their sons to workout.