Full Idea
A person's will is the effective desire which moves (or will or would move) a person all the way to action. The will is not coextensive with what an agent intends to do, since he may do something else instead.
Gist of Idea
The will is the effective desire which actually leads to an action
Source
Harry G. Frankfurt (Freedom of the Will and concept of a person [1971], §I)
Book Reference
'Free Will', ed/tr. Watson,Gary [OUP 1982], p.84
A Reaction
Essentially Hobbes's view, but with an arbitrary distinction added. If the desire is only definitely a 'will' if it really does lead to action, then it only becomes the will after the action starts. The error is thinking that will is all-or-nothing.