“Therefore I tell you, do not be anxious about your life, what you will eat or what you will drink, nor about your body, what you will put on. Is not life more than food, and the body more than clothing?Look at the birds of the air: they neither sow nor reap nor gather into barns, and yet your heavenly Father feeds them. Are you not of more value than they? And which of you by being anxious can add a single hour to his span of life? And why are you anxious about clothing? Consider the lilies of the field, how they grow: they neither toil nor spin, yet I tell you, even Solomon in all his glory was not arrayed like one of these. But if God so clothes the grass of the field, which today is alive and tomorrow is thrown into the oven, will he not much more clothe you, O you of little faith? Therefore do not be anxious, saying, ‘What shall we eat?’ or ‘What shall we drink?’ or ‘What shall we wear?’  For the Gentiles seek after all these things, and your heavenly Father knows that you need them all.  But seek first the kingdom of God and his righteousness, and all these things will be added to you. “Therefore do not be anxious about tomorrow, for tomorrow will be anxious for itself. Sufficient for the day is its own trouble.  Matthew 6: 25:34
In this short section of Scripture Jesus uses the word “anxious” five times and the word “worry” and worried” are used to convey the same idea.  Thayer’s Greek definition means to be in a state of anxiousness, or deeply troubled with cares. The basic Greek word form means to be distracted.
One of the strongest emotions that God placed within man is fear. In the normal sense of the term, fear is just fine. Fear can be reality based or it can be based in thoughts that have no connection to the immediate reality.
Fear has valuable uses. But fear, like other emotions can be abused. It may be allowed to control us rather than be controlled by us. Someone who is overly fearful and is being controlled by their fears may become  paralyzed by their fears and may appear catatonic. 
Anxiety refers to a general feeling of tension and concern that something fearful may happen.
It is based on “what if.”  Anxiety is often the result of wrong thinking. We get an anxious thought, and begin to ruminate on it, meditate on that thought. As we roll it over and over in our minds it becomes more real and more probable that it will come to pass. We begin to tell ourselves it will become reality when we have little to no factual reason to think so.
This causes our heart rate to rise, palms to sweat, breathing to become rapid. By our thoughts, we have manipulated our bodies into responding as though we are in trouble. It is not good to live on this plane of anxiety it is very stressful on the mechanics of the body.
Often times, we worry for nothing, because events do not transpire or take place as we fear. Besides, what can you do about most stuff anyway? Not much, for many things are way beyond our puny attempts to control them.
Worry also indicates a lack of understanding of God’s sovereignty. If we have faith and trust in a God who is faithful and has all events in His hand then why worry? It says to us we do not truly believe God will work out all things for our good.
Our passage in Matthew then says we should work on problems about which we can do something. 
 “Worry is anxiety over circumstances beyond our control. Worry is based on the fear that God is not control of our lives. It is a self-inflicted panic that is the opposite of confidence in God.”  From Overcoming Life’s Toughest Problems, Dr. Ed Hindson, Associate Pastor Rehobeth Baptist Church
By-products of our thinking means “our present state of mind.” We think ourselves into a state of worry and anxiety and fear. For example, if we judge a situation to be scary (car stuck on train tracks) we will feel afraid. By the same token, if we judge a social situation to be scary, we will feel afraid.
The bottom line on worry is that worry is sin!
The original definition of worry we looked at said that worry, anxiousness and unreasonable fear is sin. While the sin is rooted in our hearts, it’s propelled outward by unbiblical thinking which leads to unbiblical actions.
Why is Worry Sin?  It shows a lack of faith in God (Matt. 6:25-34), is forbidden by God (Matt. 6:34; Phil. 4:6-7), and can destroy the body by creating things like ulcers (1 Cor. 6:19).
God guarantees help and hope to worriers! He has already made a way though whatever situation we are presented with- the Word applied to our lives by the power of the Spirit. This is very hopeful for us. It means there are answers
Remember your word to your servant, in which you have made me hope. Psalm 119:49 ESV
We do not have to live as slaves to any sin as Christians. The sin we habitually commit is something we can overcome in part by learning and holding to a sound, foundational theology, based on faith in God and His trustworthy Word.(Rom. 6:6,7).