As a retired English professor in New York, I never in my life heard a student, or anyone else for that matter, say, "I had to motivate to get to class"--not even colloquially. It sounds strange to my ears. But then again, I have not been teaching for the last ten years. Languages change under our very noses as we speak! What university do you attend where you ear your "idiotisme" used? I have heard for years now, "Have a good." Are you drawing a parallel here syntactically between the construction of these two expressions with transitive verbs: "to motivate" and "to have"? At least one might argue that "good" is used here as a noun in a similar manner that the French use adjectives as nouns: "le bon," "le mal," "les biens."