Chovos Halvavos continues explaining how the ten Shaarim build upon one another. Once we recognize Hashem's absolute oneness, learn to see Him in the world around us, and devote ourselves to His service, we come to understand that everything we do must be directed toward Hashem alone — even ordinary activities like eating and sleeping.

This recognition leads us to humility (Shaar HaKniyah), and when we inevitably fall short, to teshuvah (Shaar HaTeshuvah). But how do we know where we're falling short in the first place? That's where Cheshbon HaNefesh comes in — learning to examine ourselves honestly and measure how well we're fulfilling our obligations to Hashem.