Never been a fan of affirmations; one of my spiritual teachers back in the late 1990's pointed out that our body wisdom is much smarter than words we speak. He said "If you're standing in front of the mirror saying affirmations you don't really believe, the person in the mirror KNOWS you're lying, so it won't work."

The best motivation tends to be to apply yourself consistently to something and seeing that it WORKS. Then, with that in mind, the affirmations start working because you're no longer lying to yourself.

Affirmations work best as confirmations to support something you're already on the way to succeeding at.