We can only do the things which we have control over. Other things which are beyond our control cannot be changed by us, so why do we worry. In Luke 12, Jesus warns us to avoid greed and not to be anxious in our lives over things we cannot control. In fact, Jesus tells us that we should seek the Kingdom of God and our needs will be met.
In the Bible, anxiety means unduly worry about things that are beyond your control. Believers of Christ are not to live with anxiety. As human beings, we will have worries, but Jesus warns us about worries that are not spiritual. Some worries are important and need our attention, such as worry about being obedient to God. There are other worries that occupy our minds, and we do not involve God with those worries.
We need to bring all our worries to God. Jesus also warns us not to worry about what is beyond our control. We worry about things that are not essential. (Luke 12:22-23) When we do this we start not to appreciate the things that God has given us. Jesus also warns us not to worry about the things we have no control. (Luke 12:25-26) If we cannot do anything about these things, than why worry. We cannot go beyond our capacity, but we can maximize our potential (Luke 12:24).
A heart that falls into anxiety cannot appreciate what God has given us or what is at hand. Much the same a heart that falls into anxiety does not have faith and that faith cannot grow.
How can a believer avoid falling into anxiety?
We will find ourselves in situations that ate beyond our control. This is life. Therefore we need to have a heart that fears God. A heart that fears God acknowledges that God is in control and is able to understand God's sovereignty. Although we may lack, we will know God is in control and give what is needed to meet His purposes. Acknowledge the Lordship in your life and you will guard your heart from anxiety.
We must also seek the kingdom of God daily. We need to seek His ways. In other words, we must make an effort not to be anxious. We need to refuse to fall into anxiety. Speak what Jesus has spoken to your life. Master your fears, your emotions.
The enemy wants you to be afraid of those things you cannot control and to become powerless towards the things you can do. Do you what you can and leave the rest to God.