And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect will of God. Romans 12:2
A lot of the way we think have been influenced by our surroundings; family, television/movies, media, friends. We tend to take on the thoughts of those that seem to be most common for us. If we are constantly around people who are negative, then we become negative. If we are around people who are positive, then we tend to have a positive attitude. Whatever you are exposed to the most, is usually what attitude you will take on.
Though most of our thought processing was developed while growing up with our family, there is still some retraining of our minds that needs to be done. If you grew up in a home where profanity was used to express yourself while angry, then more than likely you express yourself the same way. If you are use to people solving conflicts through the use of violence, then more than likely that's how you try to resolve conflict. However, if you grew up in an environment where people remained calm and sat down to discuss problems that have occurred, then you would more than likely respond the same way.
There is this saying that "children learn what they live." This is so true. Your familiarity becomes your normalcy. Good or bad.
We are informed in Romans 12:2 not to conform to the thinking of the world, but be transformed by the renewing of our mind. Meaning we have to retrain our brain. We have to put those thoughts that we have so commonly, and start to think the way Jesus thinks. And inorder to do that, we have to study His word.
One thing I have learned is that the more you read the Word of God, and apply it to your daily life, the more you start to think and behave like Him. Things that you thought were so important, or that you couldn't live without, once you find out that they don't line up with the Word of God, you are less incline to do them, which eventually result in you not doing them at all.
That's why it is so important that we allow God to be a part of our lives and to take top precedent in it. He is the only One who can provide us with the change we so desperately need to make.
Let this mind be in you, which was also in Christ Jesus. Philippians 2:5