There are certain things that have a cascading effect. Sin leads to sin leads to sin; where sin abides, sin increases. Where faithfulness abides, faithfulness increases. Over the ages, i'd like to say God has, in some aged-like-fine-wine sort of way, become more faithful, but that's not so. The moment of absolute faithfulness to His people was the moment when He said, "Let there be light!"
I say this because He already existed as omniscient and total. He did not need light, for He was already the light (we are given the image of the Spiritual "light" of God in Revelation 21, where it says, "And the city has no need of sun or moon to shine on it, for the glory of God gives it light, and its lamp is the Lamb."). That means the first Word of creation was for us, not His, yet it was for His glory.
Without getting too far off-track, let me explain the cascading effect; if you have a seed you can plant it and it will grow; if properly pollinated, and granting you don't cut the bloom(s), it will go to seed. If it is allowed to go the way of nature, it will drop several seeds, each one creating a new plant. Each one of those will multiply and, before several seasons have passed, one seed has taken over an entire field.
Another example is the all-too-familiar saying, "One bad apple spoils the bunch." Basically, during the decomposition process of certain fruits, ethylene is emitted, and that speeds the ripening process and, soon thereafter, rots neighboring fruit prematurely. One rotting apple in a bag or basket causes the adjacent to begin to decay, and it subsequently "infects" the next, and so forth. Potatoes do this, too.
So there are two metaphors in nature for this effect, one showing how good things multiply if left to their natural devices, and one showing how things turn sour if not quarantined immediately.
To apply this in the Spiritual, as said, sin creates sin successively. What starts as "minor" sins, such as envy, can, if not put into submission, grow into a "major" sin, such as theft. Anger turns into hate and then into violence and finally into murder. Lust into adultery, gossip into slander, and so on. This is why the emotion of sin is the same as the sin itself. It must be killed before it takes root, before a bruise on the apple festers and spreads.
Likewise, faithfulness does the same; one act of faithfulness will, if not put into submission, result in another. Giving a few cents could, through the same process of virulence, eventually lead a person to buy lunch for a stranger or far better things.
These are but simple examples, and there are far more profound ones, but they suffice for the intended message.
And, while i could never hope to be an example of sinlessness (that is Jesus alone; i'm merely a shade of the first Adam that is trying to stand in the Light of the Second Adam), i've come to understand the key ingredient to quelling sin; love. That sounds generic and cheesy, but it's a very solid truth. A great love results in great faithfulness; if you love your spouse you will not cheat on her, if you love your child you will not withhold necessary things, if you love your parents you will not do what they said not to. On the contrary, if you love your wife you will love showering her with affection and adoration, if you love your child you will discipline them and cherish them, if you love your parents you will do what they ask of you without grumbling. Love creates devotion. To love God is to obey Him. To love God is to honor Him. To love God is to run to Him in times of distress, as a child to their Father.
I have tried to fight sin on my own terms, in my own means, and failed every single time. This is no coincidence. The spirit is willing, but the flesh is weak, and that's not an excuse; it's a fact. The times i've run to God, cried out, "I love You" to Him when being assaulted, though, He turns my focus away from whatever it is that's leading me away and turns me back to Him.
This is why loving God is the greatest commandment; it causes us to eagerly obey the others. This is why loving our neighbor is the second; it causes us to get the focus off the bad of ourselves (sin) and onto the good of others. In other words, our desire for sin becomes a desire for God when we love Him and others instead of ourselves. Make a point of doing a small act of love and it will beg another. Continue sowing the seeds of faithfulness and it will turn into joyous servitude, but will also turn you away from prideful sin.
Our cure for sin is genuine love, for God and for our neighbors/enemies. Here's how; envy, when quelled with love, is turned into generosity, anger is into hope for the object of your bitterness' well-being, gossip into encouragement, et cetera.
Abide in love, and you will abide in obedience and uprightness. Where sin is sown, sin will continue to spread. Where love is sown, love will abound.
If we seek first the kingdom of God and His righteousness, joy in obedience as well as refuge from Satan's attacks shall be added unto us (i firmly believe these to be included in "all these things". After all, if seeking that first had no Spiritual promise it would hardly be meritorious, and every last word of Christ is laced with merit.