Her only levity is patience (14)
Grown-ups are always telling little kids to be patient. Often, it means waiting, but sometimes it means persevering: for example, trudging through the mall with your mom when you're tired and cranky and jealous of your baby brother who gets to ride in the stroller. "Perseverance" is one synonym of "patience." But the link to lightheartedness is unclear. The turtle is no Energizer Bunny, so what's with the levity? Must be a private joke. Turtle's got a secret. And apparently it's what keeps her going.