As born-again believers, we have the privilege to speak the language of the Kingdom of God. The language of the Kingdom is powerful and mighty. Kingdom language says, "I can!", "I believe", "I am brave", "I am victorious". This is not a mantra or the "power of positive thinking", which is contingent upon human ability. It is the supernatural word of God at work in every area of our lives--our minds, our bodies, our relationships, our families, our finances, etc.
As with any foreign language, one must study, meditate, pray, and declare(verbally speak aloud) the word of God in order to learn the language of the Kingdom. As we study the Bible, God's spoken word, our speech/language and thinking begins to change and shift from a place of negativity, doubt, and pessimism (because this type of speech and thought does not exist in the Kingdom of God) to a place of hope, expectation, anticipation, belief, and encouragement.