This world is full of things that are not of God.  As Christians, we should not be conformed to the world and its destructive tendencies.  This in of itself is a fight, because we live in a worldly body that is full of sin.  Renew your mind daily by the reading of His Word.
Romans 12:2 – Do not conform any longer to this world, but be transformed by the renewing of your mind.  Then you will be able to test and approve what God’s will is – his good, pleasing and perfect will.
Instead, we should look upon our Lord and Savior, Jesus Christ, to be made more into His image, being sanctified by the washing of the Word.  The world has nothing to give us that we need or must have.  God is the one that provides for our needs.  His truth and His Word bring refreshment to our souls.  We do not live by bread alone, but by His Spirit.
Always be on your guard and prepare to fight!