Finding words that have meaning for you (in a positive way) can change the way you feel about your day.
The affirmation above will work for you if you grew up hearing the word 'incredible' from parents, teachers etc when something good happened in your life.
In general, affirmations work if your heart and spirit are impacted when you speak them out loud.
So, always try the affirmation on for size to see if it delights, inspires and encourages you.
Other variations of this affirmation can be:
"I expect something awesome to happen in my life today."
"I expect the miraculous to enter my life today."
The point of the affirmation is not to be disappointed at the end of the day when 'nothing incredible or fantastic occurred (in your perception)."
The point is to create a mindset through daily repetition that leads to you finding the incredible and allowing it into your life when you see it.
Best of luck.
And wishing you a most delightful, brilliantly beautiful weekend.