Lyric discussion by chubigans 

Cover art for Lives lyrics by Modest Mouse

I think the "my mom is a witch part" is about his mom being a pagan. But I think he put it in the song because it's a contrast to what he's singing about. He's singing about the fact that people don't live their lives to the fullest. Well, his mom is being her own person in this world and he likes the fact that she is living her own life.