There are many methods promoted to fight sin and overcome it.
If you look at the armour that God has provided for a Christian, most of them are passive armoury, there are only 2 items in the armoury which you have to actively use. That is all you need to fight sin once you are saved. Let me clarify.
Items in the Armoury of God as given in Ephesians 6: 14 – 17.
Helmet of Salvation: helmet is armoury that you put on, that’s it. You then do not do anything further. Just make sure it stays in place.
Breastplate of Righteousness: you put on a breastplate, it remains in place, you do not do anything further.
Loins girt about with truth: again, you put on your belt, that’s it.
Shield of Faith: a shield is something that you have to use, you cannot just pick it up and stand, depending on the direction of attack you would move it around to protect yourself.
Sword of the Spirit (Word of God): you have to use your sword on the enemy, not just stand there with the sword in your hand.
Feet shod with Gospel of Peace: you need to put this on and walk i.e. proclaim the gospel.
If you look at the above, there are 3 items in the armoury that you put on, and 3 that you have to put on / take on but the onus is on you to use it.
Proclaiming the gospel of peace is an offensive weapon against satan and the world.
However for an attack against you i.e. sin/temptation etc., there are just 2 weapons in God’s armoury that you use, one the Shield of Faith and second, the Sword of the Spirit.
To put it in more simple terms, ALL that you need and what God has provided for you to overcome all sin and temptation is Faith and (in) the Word of God.
The best example being Jesus when He was tempted, He overcame the devil by the Word of God. He obviously proclaimed the Word because He had faith in it, He truly and fully believed it.
To sum it up, it is not doing things for God or going to church or doing penance or beating yourself up that gives you victory once you are saved i.e. a child of God, it is simply by proclaiming the Word of God with Faith against whatever comes your way.
The passive armoury is already yours once you are saved, put them on and leave them there. But learn every day how to be proficient and skilled in fighting with the weapons that you have to manoeuvre/use yourself.
“Blessed be the Lord my God, who teacheth my hands to fight, and my fingers to war.” – the Bible.