Even though self-control is a fruit of the Spirit, it still requires our active participation. We can quench or hinder the Holy Spirit’s work in us by the decisions we make.
Galatians 5:22–23 lists the "fruit of the Spirit" with self-control being one of them. Self-control (“temperance” in the KJV) is the ability to control one’s own desires and passions. It involves moderation, constraint, and the ability to say “no” to our baser desires and fleshly lusts. Another way to say it is self-discipline. Self-control as a fruit of the Spirit is a bit of a paradox. How can the ability to control oneself be the result of being controlled by someone else? We must actively cooperate with the Holy Spirit by presenting our bodies to Him, but it is still the Holy Spirit doing the work in us to allow us to be self-controlled (Romans 12:1–2; Philippians 2:12–13). We make choices that affect the Spirit’s work and can either be controlled by the Spirit, or we can quench and hinder His work (Ephesians 4:17–32). Each aspect of the fruit of the Spirit works in concurrence with the others.
The Bible teaches that, in a certain sense, the unbeliever has no free will. There are influences beyond his control. Unbelievers are "slaves to sin" (Romans 6:16–20). Our sinful nature "predetermines" us to choose selfish, harmful behaviors, and our fallen world aids the process. Without Christ, we are not free to completely release our thoughts and actions from sinful influences and simply choose what is good. That's where the Holy Spirit comes in. As He works in a believer's life, the fruit, or result, is that the believer can pull away from the determinant of the sinful nature and make a truly independent choice. That is the first step of self-control. The freed self then has choices to make, and he finds that the range of choices has broadened. Instead of choosing one sin over another, the new man in Christ can make choices based on love for God and rooted in the wisdom of God.
Whenever we follow unhealthy appetites or society's lies, we limit our options in the future. A sinful act is another step down a dead-end road; the more steps we take, the harder it gets to make an independent choice in the future (James 1:12–18). We can enjoy God’s best and experience the most freedom when we use our self-control to submit to Christ (John 15:1–17). His Word brings life. Christ allows us to be what we were designed to be, to display the glory we were created with. His Spirit produces self-control in us, the ability to say "no" to fleshly lusts and live in moderation and wise constraint. Indulging in sin enslaves and destroys us. Self-control frees us to live for Christ.