1) You present your opinion on a given subject in a consistant way—just so the other person doesn't forget. That shows dedication.
2) You emphasise your point of view—just so they don't think you've changed your mind. That shows good teaching and communication skills.
3) You insist on your opinion being understood. That shows your strength of purpose.
The latest news demonstrates how these sterling qualities were used to save a life.

But over the course of a day’s bed rest, his condition worsened to the point that he was rushed to A&E. Doctors were initially baffled. But when his body began to shut down from multiple organ failure caused by a deadly infection that had entered his bloodstream, there was nothing more medical staff could do for him.
He went into a coma. Members of his family remained at his bedside 24 hours a day, speaking to him. Instead of despairing, his wife gave him a piece of her mind, insisting, over and over, that he get better for her and their two sons.
Six days later, he made a miraculous recovery.
Unbeknown to them, the forty-two year old man, had been heard every word. He said, “She never lost faith in me, and I genuinely think that her constant support helped me to make it through.”
Source: Express.
So you see, the constancy, dedication, emphasis, teaching skills and downright strength involved in nagging can be used to good effect if similar circumstances happen to you. Persevere with your practice. Speak on, naggers, speak on.