The LORD's lovingkindnesses indeed never cease, for His compasssions never fail. They are new every morning; great is Thy faithfulness (Lamentations 3:22, 23).
In a general sense, your emotions are a product of your thought life. If you are not thinking right, if your mind is not being renewed, if you are not perceiving God and His Word properly, it will be reflected in your emotional life.
One of the best scriptural illustrations of the relationship between perceptions and emotions is found in Lamentations 3. In verses 1-6, Jeremiah expresses despair as he wrongly perceives that God is against him and that He is the cause of his physical problems. In verses 7-11, 18, he vents his feelings of entrapment and fear. If your hope was in God, and these words were a correct portrayal of God, you would probably feel bummed out too.
What was Jeremiah's problem? His perception of God was way off center. God wasn't the cause of his affliction. God isn't a wild beast waiting to chew people up. But Jeremiah wasn't thinking right, perceiving right, or interpreting his circumstances right, so he wasn't feeling right or responding right either.
Suddenly, Jeremiah's countenance changes: "This I recall to my mind, therefore I have hope. The LORD's lovingkindnesses indeed never cease, for His compassions never fail. They are new every morning; great is Thy faithfulness" (verses 21-23). What a turnaround! Did God change? Did Jeremiah's circumstances change? No. His perception of God changed and his emotions followed suit.
You are not shaped so much by your environment as you are by your perception of your environment. Life's events don't determine who you are; God determines who you are, and your interpretation of life's events determines how well you will handle the pressures of life. In reality we have very little control over our emotions, but we do have control over our thoughts, and our thoughts determine our feelings and our responses. That's why it is so important that you fill your mind with the knowledge of God and His Word. You need to see life from God's perspective and respond accordingly.
Lord, continually adjust my perception of my environment to match Your perspective found in Your Word.