In 1949, Donald Hebb, a Canadian neuropsychologist, wrote the well known phrase: “Neurons that fire together wire together.”
Basically what we think, feel, say, and do become imprinted in thousands of neurons that together form a neural net. The more a thought, feeling, word, or action is repeated the stronger the network becomes and the easier it is for those particular neurons to fire in the brain.
As you might have imagined the stronger the net the harder it is to unwire and rewire them to function in a more desirable way.
Welcome to the human experience. This is why it is so challenging to make shifts in our habits especially as we get older, but don't loose all hope. If a change is what you are looking for, explore the 51% rule (as described by John Douillard in the 3 Season Diet).
It says that if we put a habit into practice a little bit more than half of the time chemical change will begin to happen. Whether its a negative mantra you think to yourself, or a junk food habit, or a style of communication that doesn't yield great results the 51% works and takes off the pressure of needing to do it 'right' 100% of the time.
Neurons work like muscles, if you don't use them they won't fire as quickly, and eventually will atrophy making more space for life enhancing neural networks to strengthen and carve out new ways of thinking, feeling, saying and doing.