Motivating an unmotivated student

One student didn't want to write a letter to her family, she was unmotivated and said she didn't have anything to write about. I asked her what her favorite subject is and she said she didn't have one. She is a student that I have power struggles with and I could tell that she was in one of her stubborn moods so I knew I had to find a different approach. I told her to look at me, in my eyes and then I distracted her from her bad mood by commenting that we had the same necklace on only mine was black and hers was pink. That seemed to perk her up, so I then asked her what kinds of things she had been reading lately. She said she read time for kids about the presidential election so I asked if she would like to write about that. She said yes, and I said would be back in my five minutes to check on her, I also added, "and I really will be back" and I was consistent with that. She ended up full page letter about Barack Obama and how she is going to vote for him, she wrote "not to be rude or anything but John McCain is too old!" When she was done she came to read it me and she was so proud and excited, and read her letter with great expression. It made me feel very good.