Understanding the subtle workings of one's mind is the key to faith and attaining Buddhahood in this lifetime.

Buddhism Day by Day

Wisdom for Modern Life by Daisaku Ikeda
Friday, February 1, 2013:

 

While controlling your mind, which is at once both extremely subtle and solemnly profound, you should strive to elevate your faith with freshness and vigor. When you do so, both your life and your surroundings will open wide before you and every action you take will become a source of benefit. Understanding the subtle workings of one's mind is the key to faith and attaining Buddhahood in this lifetime.