I have always been a little skeptical of the use of self-motivating statements. ScienceDaily has an item on the subject. (here)
Little research exists in the area of self-talk, although we are aware of an inner voice in ourselves and in literature. …Recent research by University of Illinois Professor Dolores Albarracin and Visiting Assistant Professor Ibrahim Senay, along with Kenji Noguchi, Assistant Professor at Southern Mississippi University, has shown that those who ask themselves whether they will perform a task generally do better than those who tell themselves that they will…The participants showed more success on an anagram task, rearranging set words to create different words, when they asked themselves whether they would complete it than when they told themselves they would… in a seemingly unrelated task simply write two ostensibly unrelated sentences, either “I Will” or “Will I,” and then work on the same task. Participants did better when they wrote, “Will” followed by “I” even though they had no idea that the word writing related to the anagram task.
Why does this happen? Professor Albarracin’s team suspected that it was related to an unconscious formation of the question “Will I” and its effects on motivation. By asking themselves a question, people were more likely to build their own motivation…”The popular idea is that self-affirmations enhance people’s ability to meet their goals,” Professor Albarracin said. “It seems, however, that when it comes to performing a specific behavior, asking questions is a more promising way of achieving your objectives.”
The idea that something in consciousness is going to fool or bully the mind/brain, seems pretty weird - but posing a question and making that conscious would prompt planning and this is not trying to fool or bully oneself.