In Mackenzie’s own words, she did not write “Grow Old” — it wrote her. As she wrote, the words came effortlessly, despite her not quite knowing what they meant. Ever since the song came to her, she’s spent a long time trying to figure out what it’s about. The longer she lives with it, the meaning reveals itself more and more. Since she always believed she’d kill herself young, Mackenzie never thought she had a future. But, as she recovered, she realized she did, in fact, have a future to look forward to. In tandem, she also realized she had never taken the time to discover herself because she really never felt like wasting time investing in a life she believed would be very short. “Grow Old” is about the process of discovering who you are and who you’re going to be.