Proceed with an attitude of utter conviction

In her book Dr. Kato Lomb lists her 10 commandments for language learning. The tenth is to be firmly convinced that you are a linguistic genius.

Attitude is that important.

As Henry Ford said:

Whether you think you can, or you think you can't, you're right.

But I think that there's more. It's possible to inflate your confidence to some extent, but not as much as if your conviction was based upon a solid foundation.

(The metaphor of a house built on sand or on rock fits right here.) 

What are those expressions called - when you repeat positive thoughts to yourself? Oh yes, self-affirmations. It seems to me that that practice wouldn't work so well in a vacuum.