The 18th century philosopher Immanuel Kant most famously held the view that moral behavior is driven by a sense of duty rather than desire.
Such a view continues to be popular, and is now most famously defended by Christine Korsgaard. Against such a view, we might worry that people only do their duty when they want to do so. After all, when someone does their duty freely and without being forced, doesn’t that just show that they wanted to do so?