We can observe our thoughts and actions and make decisions about them. Biblical principles such as “bringing all thoughts into captivity,” “renewing your mind,” “casting all your cares,” and “being anxious for nothing” become less difficult when we realize God has given us the equipment to do these things.
God has given us grace to think correctly and when we do, we will have more victory in our lives. If you are constantly negative, start asking God to help you in the area of your thinking. Are you watching things on TV and listening to talk radio that is effecting you negatively and causing you to be upset all the time? Start listening to podcasts and listening to sermons that will uplift you.
According to Dr. Carolyn Leaf, wrong choices cause brain damage and right choices enhance brain function.  Deuteronomy 30:19 (NLT) says, “Today I have given you the choice between life and death, between blessings and curses. Now I call on heaven and earth to witness the choice you make. Oh, that you would choose life, so that you and your descendants might live!”
Read “Switch On the Brain” by Carolyn Leaf.
-Pastor “Switch on the Brain” by Carolyn Leaf. Chapter 2 pg. 45