Sometimes we get bad news, or someone irritates us and steps on our last nerve. Other times we may hear or see something that hurts us, or makes us fearful. We may have an occasion where something worries us about the future. Those things often don't disappear right away.
Later on you might say to yourself, "Why am I irritable," or "why am I in such a foul mood." Think backwards until you discover what caused it. Then what?
First of all, pray over that concern. Give it to God, "[C]asting all your care upon Him, for He cares for you" (1 Peter 5:7 NKJV). As Paul reminds us:
Be anxious for nothing, but in everything by prayer and supplication, with thanksgiving, let your requests be made known to God; and the peace of God, which surpasses all understanding, will guard your hearts and minds through Christ Jesus (Philippians 4:6-7).
Another thing we can do is to "take our thoughts captive" — we don't have to believe everything we think, but can challenge our thoughts with God's truth. The apostle Paul said:
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 (2 Corinthians 10:5).
Remind yourself about what God's Word says about your blessings in Christ.
He will never leave you or forsake you (Hebrews 13:5).
For God has not given us a spirit of fear, but of power and of love and of a sound mind (2 Timothy 1:7).
And my God shall supply all your need according to His riches in glory by Christ Jesus (Philippians 4:19).
You [God] will keep him in perfect peace, whose mind is stayed on You, because he trusts in You (Isaiah 26:3).
We are still human, so we are still affected by our emotions, but we can be aware of emotional residue and how it impacts our thoughts, feelings, and actions. Let's recognize it, pray about it, and live above it.
Thanks be to God, who gives us the victory through our Lord Jesus Christ (1 Corinthians 15:7).