"Above all else, guard your heart, for everything you do flows from it." Proverbs 4. 23
Saint Augustine, the fourth century luminary from North Africa, advises that self knowledge is complementary to knowledge of God. In other words, to become fully alive we need both a relationship with God and a realistic awareness of ourselves. This self-awareness will include both negative and positive features.
In his letter to the church in Rome (chapter 7, verse 19), the apostle Paul shares his weakness in a moment of unusual candour. He expresses what so many of us experience, that he knows what he should not do but sometimes feels powerless to resist the temptation. On another occasion the same Paul, still the most influential voice in the church after Jesus, voices his frustration over a niggling impediment, which he refers to as "a thorn in his side" (2 Corinthians 12. 7-9).
None of this is false modesty. Knowing one's limitations and weaknesses keeps one humble. It renders one open to the gifts of others and, most importantly, to the grace of God who bears with our mistakes and short-comings and equips us so that, despite them, we have everything necessary to fulfil his purpose for our lives.
In the Old Testament book of Proverbs, the Teacher directs attention to our hearts. This is not a reference to the physical organ which pumps blood around our bodies but to the invisible will that directs our lives: what we do, think, believe &c. How do we guard all that? By treading carefully, watching what we feed our minds with, checking ourselves before acting and reacting, being diligent in our prayerfulness. We might sum it up as a "healthy self-awareness", which is the bedrock for a healthy appreciation of God and out fellow creatures.