An incantation is a special type of affirmation. What's unique about incantations is that they are usually written as rhymes. The catchy phrasing and rhythm make it easy to remember an incantation. Don't worry about the literary quality of your incantations; just follow the same guidelines for creating affirmations, then make your statements rhyme.
Incantations can be as short as two lines or as long as your imagination and intention dictate. You can use an incantation in the same way you'd use any other affirmation. Although it's perfectly okay to merely write an incantation, more often they are spoken aloud. Because incantations feature both rhyme and meter, you may enjoy putting them to music and singing them.