Every human being wants to experience positive change in the conditions around him or her. No right-thinking person enjoys stagnation or retrogression. The reason being that, positive change is reflective of progress. It conveys the idea of the presence of life—only things that have life in them grow. However, the natural human tendency is to look to outward factors as the determinants of change. Lasting change, however, originates within a man or woman—you become rich in your heart before it manifests in your circumstances; you receive your healing in your heart before it manifests in your body. Jesus refered to this situation : “A good man out of the good treasure of his heart brings forth good things, and an evil man out of the evil treasure brings forth evil things.” (Matt 12:35). It is what you treasure within you that basically and ultimately defines you. 
    You may be familiar with the Psalm that reads thus : “Blessed is the man who does not walk in the counsel of the wicked or stand in the way of sinners or sit in the seat of mockers. But his delight is in the law of the LORD, and on his law he meditates day and night. He is like a tree planted by streams of water, which yields its fruit in season and whose leaf does not wither. Whatever he does prospers.” (Ps 1:1-3 NIV). The first word of the verses above ‘blessed’ is noteworthy because of its richness. To understand the depth of that word, let us see how the Amplified version of the Bible renders it : “BLESSED (HAPPY, fortunate, prosperous, and enviable)…” (Ps 1:1). Every one of us wants to be happy, prosperous, and enviable—the qualities of a life that is truly blessed. Further interesting is the fact that the blessed life is God’s will for you : “The blessing of the Lord makes one rich, And He adds no sorrow with it.” (Prov 10:22).  “Beloved, I pray that you may prosper in all things and be in health, just as your soul prospers.” (3 Jn vs 2).
    However, the blessed man of Psalm 1 did not accidentally become happy, fortunate, prosperous, and enviable, and neither will you. The obvious, outward indications of positive transformation and prosperity, such as yielding fruit in season and retaining fresh leaves, with which the Bible, by analogy, describes him are products of his identity, which, in turn, was determined by God’s word that was deeply rooted in his heart. It is what you are inwardly that ultimately determines what you attract and become outwardly. David was first a king at heart long before he became one on the throne. The contrast which God Himself drew between him and his elder brother Eliab underscores this fact : “But the Lord said to Samuel, “Do not look at his appearance or at his physical stature, because I have refused him. For the Lord does not see as man sees; for man looks at the outward appearance, but the Lord looks at the heart.”” (1Sam 16:7). It implies that the inner realities of a person’s life will eventually determine his or her external realities, assuming they are not already the same.
    Every path has a destination, and to walk in it leads, inevitably, to that destination. The good news, however, is that we can choose the path we want to follow, based on the destination to which it leads. Hence we do not have to end up in destruction. This is the reason why the Bible says, “Don’t copy the behavior and customs of this world, but let God transform you into a new person by changing the way you think. Then you will learn to know God’s will for you, which is good and pleasing and perfect.” (Rom 12:2 NLT). The way you think determines the person you are. Proverbs 23:7 says, “For as he thinks in his heart, so is he. ….”.  The expression “let God” in Romans 12:2 indicates that, even though you are born again and have the HolySpirit within, God cannot transform your personality, without your permission.
    Therefore, in order to experience positive transformation within that will eventually reflect outside, you need to “let God”—cooperate with Him. This requires that you internalize His word, by conscientiously meditating on it. The  Bible refers to this exercise in Proverbs : “My son, give attention to my words; Incline your ear to my sayings. Do not let them depart from your eyes; Keep them in the midst of your heart; For they are life to those who find them, And health to all their flesh.” (Prov 4:20-22). Our attention is more important to God than anything else. If God can have our sustained attention, He can change us. Therefore we need to “let God” by giving attention to His word. This requires both auditory and visual focus, as the scriptural text instructs : “…Incline your ear to my sayings. Do not let them depart from your eyes…”(Prov 4:21). God’s word is a living and settled reality in heaven, and should  also be that way in our hearts (Ps 119:89). The idea is to get God’s word so deeply rooted in our hearts as to enable it reconfigure our beliefs (inner realities), and bear the fruit of God’s kingdom in our lives. Remember, it is only the seed of God’s word that can produce the fruit of His kingdom. Shalom.