Here's why:
* Reflexive pronouns refer back to the subject of the sentence, indicating that the action is performed by the subject upon themselves. In this case, "you" are taking care of "yourselves."
* Intensive pronouns emphasize the subject, but they are not essential to the meaning of the sentence. For example, "You yourself took care of the problem" - the sentence would still make sense without "yourself".
In this example, "yourselves" is necessary to complete the meaning and show that the action is directed back to the subject.