In many fanfictions, Naruto might discipline Boruto through a combination of both. He could start with strict training, like how he was trained by Kakashi and others. For example, making Boruto do intense physical exercises and chakra control drills. But Naruto also understands the importance of emotional guidance. He might share his own experiences as a young ninja, like how he felt lonely at times and how he overcame his challenges. This would help Boruto understand the importance of perseverance and self - belief.
Naruto could discipline Boruto by involving him in important village matters. By showing Boruto the responsibilities that come with being a ninja from a powerful family. He might also discipline him in the way of combat. Naruto is a very experienced fighter, so he could teach Boruto new jutsus and at the same time, instill discipline in him. For instance, if Boruto is lazy during training, Naruto would make him do extra laps or spar with stronger opponents to teach him the importance of hard work.