Here's why:
* Reflexive Pronouns: Reflexive pronouns (myself, yourself, himself, herself, itself, ourselves, yourselves, themselves) are used when the object of a verb is the same as the subject. This sentence does not have a reflexive pronoun.
* Intensive Pronouns: Intensive pronouns (myself, yourself, himself, herself, itself, ourselves, yourselves, themselves) are used to emphasize the subject of a sentence. They are not essential to the meaning of the sentence, and can be removed without changing the basic meaning. This sentence does not use an intensive pronoun.
In this case, "it" is the object of the verb "set". It is not the same as the subject "I," and it is not used for emphasis. The sentence simply describes an action.