Our thoughts, what we dwell on in our minds, that is what sinks into our hearts and from our heart, our behaviours and actions come. I see so many who harbour hate, resentment and hang on to grudges... It consumes them and while it hurts us on the outside, it hurts them more on the inside.
The inability to apologize to someone is in direct correlation to a person not thinking of themselves worthy enough to be apologized to. The inability to forgive someone is a direct result of that person themselves thinking they are unforgivable. A person always needing to be right shows just how insecure they really are.
It was only when I started to see myself through the eyes of God and the total love that Jesus had for me, that my life started to change. And I see the same in those around me... my friends, my family, those I pray for... What I think and what I believe impacts me and those around me. We can think our way into or out of anything... and that's not always a good thing!
Proverbs 4:23 tells us to guard our hearts for out of it springs all life's issues. Even Jesus tell us that our thinking is wrong in Luke 12:51 saying "Do you think I came to bring peace on earth? No, I tell you, but division."
While He absolutely IS the Prince of Peace (those in Christ HAVE peace)... Jesus came to divide right from wrong, love from hate, good from bad etc. Jesus came to divide our thoughts, our deeds and our hearts. He came to show us the truth about our thinking.