Intensive pronouns emphasize, or intensify, the noun or pronoun they refer to. They can refer to any noun or pronoun in the sentence, not just a subject. Intensive pronouns are used for emphasis only — they are not objects of verbs or prepositions.
No one else was home, so I brought in the groceries myself.
The intensive pronoun myself emphasizes the pronoun I.
After waiting in line all afternoon, we were finally able to meet the queen herself.
The intensive pronoun herself emphasizes the noun queen.
One way to tell if a pronoun is reflexive or intensive is to try replacing it with an object pronoun, like me, her, or us. If you can replace it with an object pronoun and still have a complete sentence, it is reflexive. If you can't, it is intensive.
Did Sarah save any of the cookies for herself?
Did Sarah save any of the cookies for him?
You can replace herself with the object pronoun him and still have a sentence. This tells you that the pronoun is reflexive.
No one else was home, so I brought in the groceries myself.
No one else was home, so I brought in the groceries her.