Will-ful

Lucy: "I need to go roller skating."
Me: "You don't need to go roller skating, you want to go roller skating."
Lucy: "No, I need to go roller skating."
Me: "No, needs are things you need to stay healthy and alive like sleep and food and shelter and protection. You don't need to roller skate."
Lucy thinks about it for a while.
Lucy: "I WILL go roller skating."