What is the song "I Miss the Mountains" metaphorical for? What does Diana do while singing it?

In "I Miss the Mountains," Diana sings of missing the mountains, the highs and lows of feeling and excitement. She misses feeling, she sings, and as she sings, she dumps all her medications down the toilet. "I miss my life," she says. Gabe enters, suggesting what she's doing is a great idea, and that Diana is brave.