Keep positive thoughts, only...

 Philippians 4:8

Finally, brothers and sisters, 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.

There's a say that we become our thoughts...Which is why the bible tells us to only think of good things. That we should think of things that are positive, noble, praiseworthy, pure, right etc. This will result in good moods and positive attitude, to look forward to something. The opposite is true, if we think of negative things constantly, we may get into depression- something a lot of people struggle with or have encountered (myself included), anxiety, stress and so may mental issues. Our thoughts could frame the way we see life, the way we see our future. If we are negative, we are most likely to be negative in what we speak and might be negative about what's in the future. Remember the power of our tongues...

However, God has the final say; when the devil has got us in the corner with the negative thoughts, the Lord sends His angels to bring a word, just a word that would transform the mood immediately. The word that would bring hope and change our thinking that pain may last a moment, but joy comes in the morning. 

Be careful of the thoughts you have, they say our minds may be a battlefield for the enemy. Obviously the enemy would want God's children losing hope and going stray, however, the Lord pulls us back to Himself. Let us pay attention to what we keep in our minds, they say it takes a thought to replace a thought. So, replace those negative thoughts with positive ones...The ones described in Philippians 4:8.