(That's actually a pretty good analogy. The force of gravity is a reasonable approximation to the truth for nearly all everyday purposes even though conceptually it is completely wrong. Likewise with free will.)

The common understanding of free will does run into a lot of problems when it comes to issues such as habit change.

There are people debating whether or not hypnosis can get people to do something against their free will, with happens to be a pretty bad question. Questions such as can people decide by free will not to have an allergic reaction? are misleading.