Philippians 4:8 NLT
And now, dear brothers and sisters, one final thing. Fix your thoughts on what is true, and honorable, and right, and pure, and lovely, and admirable. Think about things that are excellent and worthy of praise.
James Allen published an essay in 1903 called "As a Man Thinketh". It has been popular over the years and reminds us of Proverbs 23:7 which tells us "For as he thinketh in his heart, so is he."
What we dwell on can become who we are. And this includes those we hang around with, what we watch and listen to, and what we read. In other words input equals output.
As believers we have Holy Spirit, the Spirit of Christ in us. Our spirit is one with Him. To be become more and more like Jesus in our daily walk we must practice His presence in all we do. We need complete renewal of our mind so we think like He thinks. Who we purposely associate with can have a positive or negative effect on that renewal.
When we are in our daily life of work and shopping and the other things we are involved with we are not in control of who those people are. So we remember that He who is in us in more powerful than he who is in the world. His shield of protection is upon us.