Trainor attends Nauset High School in Cape Cod, Massachusetts. She sings, plays the trumpet and studies guitar with famous guitarist Johnny Spampinato. Trainor is ashamed of her appearance in high school:
In high school, sometimes the voice inside my head was worse than any hater. I used to be miserable in high school, but I should have looked in the mirror every day and said you look so cute today. It was all in my brain. I was like I know (girls at my high school) hate me, but they probably weren’t even thinking about me.