There are two areas to our minds the subconscious and the conscious.
The subconscious mind is the part of our mind that we refer to as the deep all knowing part of our minds. The subconscious knows all there is to know. It has stored every moment every memory every breath you have ever taken and stored it.
If we look at this iceberg it is a lot like our mind. The bit about the water is our conscious mind. The part that has to deal with our daily concerns. What we have to do for the day and the things that we are experiencing in real time. The unconsious mind it the part that is below the surface the part of our mind that takes the pressure of the conscious mind. It is very big and helps deal with lots of information. Every single thing we go through or we process is stored here in the subconscious. All the information that is stored here is largely forgotten. things like riding a bike, drive a car, learning to walk or how to read is all stored here.
Every thing we have done or how we have coped or reacted to different scenarios is too stored here.
So if we found that being quite and not making too much of a fuss and keeping our thoughts to ourselves has kept us from conflict then we will repeat this because it has worked for us in the past. It isn't until we want to change that we even realise that these patterns or the way that we deal or show up are a thing.
Maybe you now want people to stop walking all over you and you want to start speaking your mind but you have ingrained in you that speaking up causes drama.
It does take time to change and if you have turned to smoking, overeating, drugs, alcohol, retreating, anger and the list is long it may take a while to change your patterns.
But doing new things (like speaking up) or working out over and over will help you to develop new patterns. Will help you to create a new habit and just as learning to drive a car took alot of steps to learn how to do it confidently. Watching the road, noticing where you are, Looking out for traffic as well as trying to change gears, put on your blinker, checking your mirrors, Using the clutch and accelerator, How to navigate corners and roundabouts etc. Now I bet you do this sometimes not every really remembering the trip but your subconscious has led you through all the steps without a second thought.
Eventually if you practice implementing new habits or patterns you will get to the point where you just do it without thought. Same way you get dressed, get out of bed and do your morning routine.