Anxious people live by what they feel.

 After they had eaten and drunk in Shiloh, Hannah rose. Now Eli the priest was sitting on the seat beside the doorpost of the temple of the LORD. She was deeply distressed and prayed to the LORD and wept bitterly. And she vowed a vow and said, "O LORD of hosts, if you will indeed look on the affliction of your servant and remember me and not forget your servant, but will give to your servant a son, then I will give him to the LORD all the days of his life, and no razor shall touch his head."

As she continued praying before the LORD, Eli observed her mouth. Hannah was speaking in her heart; only her lips moved, and her voice was not heard. Therefore Eli took her to be a drunken woman. And Eli said to her, "How long will you go on being drunk? Put your wine away from you." But Hannah answered, "No, my Lord, I am a woman troubled in Spirit. I have drunk neither wine nor strong drink, but I have been pouring out my soul before the LORD.”
1 Samuel 1:9-15 (ESV)
Hannah was anxious because she could not conceive children. Her husband's other wives continually pointed out this problem, and it was a continual source of dissatisfaction. Hannah knew the only one who could help her was God, and she poured her heart out to Him. Perhaps she would have been calm if she had known God's plans. I imagine the more she focused on those who continually pointed out her "deficit," her anxiousness grew. (There always seem to be people willing to point out our deficits.)
When we experience anxious thoughts, we need to remind ourselves of what we know rather than what we feel. If we do not know God, we will have no good option, and will suffer the fruit of anxiousness. If we know God, we will trust His character and the apparent fact that He has a plan.
Anxious people live by what they feel. Those who live peaceful lives live by what they know about God and His love for them.