This is a fixed sentence pattern, verb prototype +sth+, and. Expressing imperative sentences.
3. Analyze the sentence structure. Keeping healthy is the gerund phrase as the subject, and running, exercising and what you can do to keep healthy are the objects. So this sentence lacks predicate verbs. Exclusion C. Fitness means a whole, the predicate verb is singular, exclusion A. According to the meaning of the sentence, there is no passive meaning, choose D.