How is the word myself used differently in these two sentences: I hurt myself exercising and I saw it myself ? And for that matter, what is the difference between I saw it myself and I myself saw it ? English pronouns can be confusing, and where we place them in a sentence matters stylistically.
First, let’s remember that a pronoun works pro, on behalf of, a noun. If a noun names something directly, a pronoun refers to the same thing indirectly. Thus the noun Tom and the pronoun he, or the noun chair and the pronoun it. A pronoun has an antecedent, the word to which it refers, and that antecedent determines the gender and number of its pronoun, so that readers can easily know which noun a given pronoun is representing. Thus, Tom is a masculine singular noun, and so too is the pronoun he. Some grammars will say there are four classes of pronouns in English, others will say five, some even seven. The difference is all a matter of how one organizes the subject conceptually; which scheme you choose matters less than that you choose a way to organize the topic and stick to it. Pronouns seem to multiply quickly in many languages.
So let’s name five classes of pronouns: personal, relative, interrogative, indefinite, and reflexive. The two that will concern us here are the first and the last, the personal and reflexive. The term person in grammar refers to any entity, animate or inanimate, so a personal pronoun may point to a human being, Tom, or to some object in the world, a chair. I and we, you, he, she, it, and they are some (I stress some) of the many forms of personal pronouns in English, and their purpose is to give us a way to avoid the almost unbearable monotony which would result in saying the same noun over and over again: Tom called me today and Tom explained that Tom would not be at the meeting tonight. Reflexive pronouns, on the other hand, have a special role to play. They too, as pronouns, must refer to an antecedent, but reflexive pronouns reflect back (hence the term reflexive) to the subject of their clause as the object of the verb, telling the reader that what the subject did just landed back on the subject itself: I hurt myself exercising means that the subject is also the direct object of the verb hurt. We can recognize a reflexive pronoun by the suffix –self.
So how are we to understand, then, our second example, I saw it myself ? It’s clear that what the subject saw was not himself, but it (whatever that might have been), so myself can’t be a reflexive pronoun here; a reflexive pronoun, remember, refers to the subject of a clause when that subject is its own object. But when a reflexive pronoun wants to emphasize the subject as a subject, then it is called an intensive pronoun, because it is doing just that: intensifying or accentuating the subject as a subject. (Some grammars, be it known, will call an intensive pronoun an intensifying adjective, understanding the word myself in our example not as a pronoun in apposition to its subject, but as an adjective properly modifying the subject. Whether you buy six apples or I buy half a dozen, we both have the same number in the basket.)
And to our second question, then, of where to place the intensive pronoun—it matters quite a lot as to the style we fashion. Because English relies heavily on word order, words that work together syntactically should theoretically stay close together. In the sentence I myself saw it, the intensive pronoun myself stands directly beside its subject, I, because the two work together. That order, precisely because of its precision, strikes us as quite formal, which is good in the right circumstances and not so good in more relaxed settings. Hence the more common arrangement of I saw it myself. Here, the intensive pronoun has been postponed to the end, already the most emphatic region of an English sentence, making the intensive pronoun all the more emotionally rousing. We are to hear a more controlled emotion in the first arrangement, and a more naturally ebullient one in the second.
Pronouns are a particularly complex (which is not to say inherently complicated) department of grammar, where patience and method are to be prized. Step by step and we can see how they all work together to express just the right shade of meaning and emphasis.