“What does the Bible say about managing/controlling emotions?”……What would humans be like if we never became emotional? Perhaps we would be like "Mr. Spock" on Star Trek, as his responses to all situations seem to be purely logical, never emotional. But God created us in His image and God's emotions are revealed in the Scriptures; therefore God created us emotional beings. We feel love, joy, happiness, guilt, anger, disappointment, and fear, and sometimes these can be "false" feelings if they are based upon false premises. For example, if we falsely believe that God is not in control of the circumstances of our lives, we may experience the emotions of fear or despair or anger based on that false belief. True or not, emotions are very powerful and real to the one feeling them.……The Bible has much to say about the emotions we experience. Our emotions, like our minds and bodies, are influenced greatly by the fall of man into sin. As such, they are tainted by our sin natures. For the Christian, however, the Spirit of God who resides within us is capable of controlling our emotions and not allowing them to control us

Romans 8:9-11

But you are not controlled by your sinful nature. You are controlled by the Spirit if you have the Spirit of God living in you. (And remember that those who do not have the Spirit of Christ living in them do not belong to him at all.)10 And Christ lives within you, so even though your body will die because of sin, the Spirit gives you life[a] because you have been made right with God.11 The Spirit of God, who raised Jesus from the dead, lives in you. And just as God raised Christ Jesus from the dead, he will give life to your mortal bodies by this same Spirit living within you.

From within believers, He directs, guides, comforts, and influences us, as well as producing in us the fruit of the Spirit

Galatians 5:22-23

But the Holy Spirit produces this kind of fruit in our lives: love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. There is no law against these things!

The emotions we experience are then His emotions, produced in us so that we exhibit the benefits of His presence in our hearts-love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control. ……Out-of-control emotions are the product of a heart which is not saturated with Scripture. The way to control our emotions is to control our minds, renewing them by the daily input of scriptural principles, the knowledge of God, and meditation on His attributes. Then the Holy Spirit, along with the Word of God, will bring about appropriate emotions based on truth. When we immerse ourselves in the only means of our sanctification-the Bible-we arm ourselves with the only effective weapon against out-of-control emotions. Then we can control our emotions instead of them controlling us. In themselves, emotions are not unbiblical, but they are indications of what is in our hearts

Luke 6:45

A good person produces good things from the treasury of a good heart, and an evil person produces evil things from the treasury of an evil heart. What you say flows from what is in your heart.