By believing 1 Peter 5v7 which says ..... "Pour out all your worries and stress upon Him and leave them there, for He always tenderly cares for you".
There is a promise for every situation and for every sin that you are ever tempted to commit and for every form of unbelief that takes you off your guard and robs you of your JOY and makes your life miserable and anxious.
For example, when I am ANXIOUS about being SICK especially this time of year, then I battle unbelief with God's PROMISE of Psalm 34v19 which tells me that ..... "The righteous person faces many troubles, but the Lord comes to rescue each time" and I take this promise, Yes!!! with trepidation and trembling believing in Romans 5v3-5 knowing that ..... "we can rejoice too, when we run into problems and trials, for we know that they help us develope ENDURANCE and endurance developes STRENGTH of CHARACTER and character strengthens our confident hope of SALVATION. And this HOPE will not lead to disappointment. For we know how dearly God loves us, because He has given us the Holy Spirit to fill us with His LOVE".
When I am ANXIOUS about getting Old, I battle my unbelief with the promise of Isaiah 46v4 that tells me ..... "I will be your God throughout your lifetime until your hair is white with age. I made you and I will care for you. I will carry you along and save you".
When I am anxious about DYING I battle unbelief with the PROMISE of Romans 14v7-9 that says ..... "We don't live for ourselves or die for ourselves. If we live, it's to HONOUR the LORD. So whether we LIVE or DIE, we BELONG to the Lord. Christ died and rose again for this very purpose - to be Lord both of the LIVING and the DEAD".
when I am ANXIOUS that I may make shipwreck of my faith and fall away from God. I then battle unbelief with the PROMISE of Philippians 1v6 ...... "And I am certain that God, who began the good work within you, will continue His work until it is FINALLY FINISHED on the day when Christ Jesus returns"
Along with the promises of Hebrews 7v25 ..... "Therefore He is able, once and forever, to save those who come to God through Him. He lives forever to intercede with God on their behalf."
Let us make WAR, not with other people, but with our OWN UNBELIEF, because it is the root of ANXIETY, which in turn, is the root of so many other sins. Let us fix our eyes on the PRECIOUS and very GREAT PROMISES of God by taking up His WORD the BIBLE, and asking the Holy Spirit for help. And place and fix these PROMISES UPON OUR HEARTS so that we can fight the good fight, living by faith in GOD'S WORD and in His precious GRACE now and forever.