Identify the incorrect phrase in: "Waking up early is beneficial for one’s health and it keep you productive."

The phrase containing the error is "keep," which should be "keeps" in this context. The subject of the clause "it" is singular, and thus it requires the singular form of the verb "to keep," which is "keeps." The correct phrase would read "it keeps you productive."

Other elements in the sentence are grammatically correct. "Waking up early" serves as the subject of the sentence, and "beneficial for one's health" properly describes the subject. The sentence structure is sound, focusing on the advantages of early rising without any issues in the other phrases. The verb agreement is the only aspect in need of correction.