"Fifteen" is one of those songs that can instantly take you back to a certain time in your life. I'll never forget how excited I was to play this while getting ready for my first day of high school, even if I did go on to ignore all of the advice she gave. (Spoiler alert — she was right about everything!) Though Swift was still a teenager herself when she wrote the song, it was like she became the whole world's big sister, warning us of the pitfalls of being too naive and the importance of holding on to our best friends.