When the Bible says, "Set your affection on things above, not on things on the earth." (Colossians 3:2), it means that we must continually choose, twenty-four hours a day, to keep our minds on the positive things of God.  The apostle Paul provides a great list by which we can evaluate our thoughts: "brothers, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable—if anything is excellent or praiseworthy—think about such things" (Philippians 4:8).

So how do you ascertain the source of a thought?  Easy.  If it's a discouraging, destructive thought; if it brings fear, worry, doubt, or unbelief; if the thought makes you feel weak, insecure, or inadequate, I can guarantee you that thought is not from God.  You need to get rid of it immediately.  If you dwell on the enemy's lies and the negative takes root, it creates an enemy stronghold in your mind from which attacks can be launched.

You must make a quality choice to keep your mind focused on the good things of God and experience His best for your life.  We must be especially on guard during times of adversity, in times of personal challenge.  When troubles strike, often the first thoughts that come to mind are not positive thoughts.  Negative thoughts and fear bombard us from every possible angle.  right there, we must choose to trust God and know that He has great things in store for us.

I will stay focused and full of hope, knowing that God is fighting my battles for me.

2 Corinthians 10:5 - "We demolish arguments and every pretension that sets itself up against the knowledge of God, and we take captive every thought to make it obedient to Christ."

from - Your Best Life Now, Joel Osteen