Which preposition to use with motivation

of Occurrences 6%

Journalists' personal entries provided a much broader range of opinions on both the strategies and motivations of all sides in the conflict than were available, particularly to Americans, on broadcast and cable television.

by Occurrences 2%

Had the Prince shown himself more susceptible to the charms of the merchants' daughters who fell in his way, this bit of romancing might claim the doubtful distinction of being Mrs. Haywood's only original secret history, but as it stands, no part of the story has the necessary motivation by passion.

to Occurrences 1%

Even so does the conceptual world bring new ranges of value and of motivation to our life.

Which preposition to use with  motivation