Who is it up to?
Rav Tzadok writes in the Likutim to Peri Tzaddik: A person possesses only the initial inspiration and choice; the rest is up to HaShem. This is indicated in the possuk: Hashiveinu! Hashem answers us: No; Shuvu eilay v’ashuvah. If HaShem would not assist us and send the blessing in our handiwork, we would not be able to do or accomplish anything. Before the blessing, it
Before the blessing, it is: La’HaShem ha-aretz u’meloah. [For accuracy purposes, he then says that even the thought process belongs to Hashem, but it seems that in the preceding line, he said differently.] However, after the blessing, when a person realizes that everything comes from HaShem, then even the aretz is given over to people, and then the actions and the thoughts can be from the person himself.