Habits are simple and mechanical in operation. People think human nature is complicated in this respect but it isn't. Whatever makes us 'feel better', is what will make us feel better in the future. Like laying down a track through the weeds that makes it easier to walk that same pathway in the future.
That's how people get started on any number of unhealthy tracks that they find themselves on, gambling, drinking, porn, sexual infidelity, anger, lust, drugs, in fact, satisfying any hunger or desire in an unhealthy way. Once someone finds a way to scratch that itch, they will want to scratch it again later, but it just takes more scratching each time to get the same effect (that's how people end up going down and down). Yes, different people have different temptations, genetics, upbringing have something to do with that, but the way sin happens is the same every time - it starts with crossing a line of conscience or upbringing, and feeling better afterwards because the itch has been scratched.
But what makes us into complicated people is the baggage we get with this desire/behaviour/desire cycle - shame, principally. So then we try to forget, either suppress the shame or the remembrance of the action, or both. We try to deny that this habit controls us. We say such-and-such is not a sin. We vow not to do it again. The different ways people deal with this is what makes people different I guess.
But one way or another, everyone becomes slaves to that which controls them.
This is human nature and was described this way by St. Paul:
14We know that the law is spiritual; but I am unspiritual, sold as a slave to sin. I do not understand what I do. For what I want to do I do not do, but what I hate I do. And if I do what I do not want to do, I agree that the law is good. As it is, it is no longer I myself who do it, but it is sin living in me. For I know that good itself does not dwell in me, that is, in my sinful nature. For I have the desire to do what is good, but I cannot carry it out. For I do not do the good I want to do, but the evil I do not want to do—this I keep on doing. Now if I do what I do not want to do, it is no longer I who do it, but it is sin living in me that does it.
So I find this law at work: Although I want to do good, evil is right there with me. For in my inner being I delight in God’s law; but I see another law at work in me, waging war against the law of my mind and making me a prisoner of the law of sin at work within me. What a wretched man I am! Who will rescue me from this body that is subject to death? Thanks be to God, who delivers me through Jesus Christ our Lord!
So then, I myself in my mind am a slave to God’s law, but in my sinful nature a slave to the law of sin. Romans 7:14-25
St. Paul goes on to describe the solution that Christ won for us by dying on the cross:
1Therefore, there is now no condemnation for those who are in Christ Jesus, because through Christ Jesus the law of the Spirit who gives life has set you free from the law of sin and death. For what the law was powerless to do because it was weakened by the flesh, God did by sending his own Son in the likeness of sinful flesh to be a sin offering. And so he condemned sin in the flesh, in order that the righteous requirement of the law might be fully met in us, who do not live according to the flesh but according to the Spirit.
Those who live according to the flesh have their minds set on what the flesh desires; but those who live in accordance with the Spirit have their minds set on what the Spirit desires. The mind governed by the flesh is death, but the mind governed by the Spirit is life and peace. The mind governed by the flesh is hostile to God; it does not submit to God’s law, nor can it do so. Those who are in the realm of the flesh cannot please God.
You, however, are not in the realm of the flesh but are in the realm of the Spirit, if indeed the Spirit of God lives in you. And if anyone does not have the Spirit of Christ, they do not belong to Christ. But if Christ is in you, then even though your body is subject to death because of sin, the Spirit gives life because of righteousness. And if the Spirit of him who raised Jesus from the dead is living in you, he who raised Christ from the dead will also give life to your mortal bodies because of his Spirit who lives in you.
Therefore, brothers and sisters, we have an obligation—but it is not to the flesh, to live according to it. For if you live according to the flesh, you will die; but if by the Spirit you put to death the misdeeds of the body, you will live.
For those who are led by the Spirit of God are the children of God. The Spirit you received does not make you slaves, so that you live in fear again; rather, the Spirit you received brought about your adoption to sonship.f And by him we cry, “Abba, Father.” The Spirit himself testifies with our spirit that we are God’s children. Now if we are children, then we are heirs—heirs of God and co-heirs with Christ, if indeed we share in his sufferings in order that we may also share in his glory. Romans 8:1-15
I consider that our present sufferings are not worth comparing with the glory that will be revealed in us. For the creation waits in eager expectation for the children of God to be revealed. For the creation was subjected to frustration, not by its own choice, but by the will of the one who subjected it, in hope that the creation itself will be liberated from its bondage to decay and brought into the freedom and glory of the children of God.
We know that the whole creation has been groaning as in the pains of childbirth right up to the present time. Not only so, but we ourselves, who have the firstfruits of the Spirit, groan inwardly as we wait eagerly for our adoption to sonship, the redemption of our bodies. For in this hope we were saved. But hope that is seen is no hope at all. Who hopes for what they already have? But if we hope for what we do not yet have, we wait for it patiently.
In the same way, the Spirit helps us in our weakness. We do not know what we ought to pray for, but the Spirit himself intercedes for us through wordless groans. And he who searches our hearts knows the mind of the Spirit, because the Spirit intercedes for God’s people in accordance with the will of God.
And we know that in all things God works for the good of those who love him, who have been called according to his purpose. For those God foreknew he also predestined to be conformed to the image of his Son, that he might be the firstborn among many brothers and sisters. And those he predestined, he also called; those he called, he also justified; those he justified, he also glorified. Romans 8:16-30