The Nurse reminded us that babies should have Tummy Time when they are awake. It helps prevent the flat back of the head and is good exercise, because they usually work hard to lift there heads to look around.
When my baby has Tummy Time (and this is more noticeable when people are watching) he just lies there and watches people walk around. He doesn't want to exercise.
He might think he doesn't need it because he is a strong boy.