When Lehi said:
2 Nephi 25: 16 Wherefore, the Lord God gave unto man that he should act for himself. Wherefore, man could not act for himself save it should be that he was enticed by the one or the other.
he is not using the way act the way we are. He isn't counting things like eating, sleeping, driving, walking, running, painting, etc... as acting. He is also not including any of the things an animal can do as acting.
He is using the word "act" to mean either choosing to submit to the will of God or to rebel against it. This is man's great power: to choose between submitting his will to Gods, or to choose to rebel against God's will.
In order to do that he needs some inclination of what God's will is or isn't. That is what the phrase "man could not act for himself save it should be that he was enticed by the one or the other" is trying to say. Without that knowledge, he may do all sorts of daily things, but none of them is to "act" in the sense that Lehi is using the phrase. To act in Lehi's sense here is to be enticed by God or and adversary and to choose to hearken or to not.