Self Control is the Fruit of the Spirit
Gal 5:22 But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, 23 gentleness, self-control; against such things there is no law.
Gal 5:24 And those who belong to Christ Jesus have crucified the flesh with its passions and desires. 25 If we live by the Spirit, let us also keep in step with the Spirit. 26 Let us not become conceited, provoking one another, envying one another. (English Standard Version)
Self control for God's children is accomplished by our being in tune with God's Spirit within us. The Spirit has instructed us about what is good and true, and He reminds us of God's will. When we learn to listen to our conscience, which has been trained by study of God's word, we will be able to resist temptation to sin as we pray to God for strength.
Self control is not about being able to control ourselves by our own strength, but it is about learning to depend upon God's truth and strength to give us the power to make good decisions. Human desires and passions are very strong, and efforts to control ourselves without the strength that God gives His children are often futile. Paul speaks to this condition in Romans 7, and concludes that only Jesus Christ can set us free from slavery to our desires.
Rom 7:20 Now if I do what I do not want, it is no longer I who do it, but sin that dwells within me. 21 So I find it to be a law that when I want to do right, evil lies close at hand. 22 For I delight in the law of God, in my inner being, 23 but I see in my members another law waging war against the law of my mind and making me captive to the law of sin that dwells in my members.
Rom 7:24 Wretched man that I am! Who will deliver me from this body of death? 25 Thanks be to God through Jesus Christ our Lord! So then, I myself serve the law of God with my mind, but with my flesh I serve the law of sin.
Paul shows that we do not make ourselves righteous by always making the right choices, because we fail. We make mistakes because of our strong human desires. When we come to Christ for salvation, we lay ourselves down in repentance, and decide to trust Jesus for salvation. We must crucify self, so that Christ may live in us.
Gal 2:19 For through the law I died to the law, so that I might live to God. 20 I have been crucified with Christ. It is no longer I who live, but Christ who lives in me. And the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me. 21 I do not nullify the grace of God, for if righteousness were through the law, then Christ died for no purpose.
Die to Self
Dying to self is part of repentance. We recognize that we have been separated from God by sin, which is spiritual death. We bury a dead sinner in baptism with Jesus, and are raised by the power of God to new life, a life enabled by God's spirit which He gives to those who obey Him.
Rom 8:3 For God has done what the law, weakened by the flesh, could not do. By sending his own Son in the likeness of sinful flesh and for sin, he condemned sin in the flesh, 4 in order that the righteous requirement of the law might be fulfilled in us, who walk not according to the flesh but according to the Spirit. 5 For those who live according to the flesh set their minds on the things of the flesh, but those who live according to the Spirit set their minds on the things of the Spirit. 6 For to set the mind on the flesh is death, but to set the mind on the Spirit is life and peace. 7 For the mind that is set on the flesh is hostile to God, for it does not submit to God's law; indeed, it cannot. 8 Those who are in the flesh cannot please God.
Rom 8:9 You, however, are not in the flesh but in the Spirit, if in fact the Spirit of God dwells in you. Anyone who does not have the Spirit of Christ does not belong to him. 10 But if Christ is in you, although the body is dead because of sin, the Spirit is life because of righteousness. 11 If the Spirit of him who raised Jesus from the dead dwells in you, he who raised Christ Jesus from the dead will also give life to your mortal bodies through his Spirit who dwells in you.
Rom 8:12 So then, brothers, we are debtors, not to the flesh, to live according to the flesh. 13 For if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the body, you will live. 14 For all who are led by the Spirit of God are sons of God. 15 For you did not receive the spirit of slavery to fall back into fear, but you have received the Spirit of adoption as sons, by whom we cry, "Abba! Father!"
Rom 8:16 The Spirit himself bears witness with our spirit that we are children of God, 17 and if children, then heirs—heirs of God and fellow heirs with Christ, provided we suffer with him in order that we may also be glorified with him.
Yes, those who are led by the Spirit of God are sons of God. The sons of God practice self control. One fruit of God's Spirit in us is self control. Thus we are taught to put off all sinful practices, by trusting God's truth and power in us.
Eph 4:18 They are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to their hardness of heart. 19 They have become callous and have given themselves up to sensuality, greedy to practice every kind of impurity.
Eph 4:20 But that is not the way you learned Christ!—21 assuming that you have heard about him and were taught in him, as the truth is in Jesus, 22 to put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, 23 and to be renewed in the spirit of your minds, 24 and to put on the new self, created after the likeness of God in true righteousness and holiness.
Eph 4:25 Therefore, having put away falsehood, let each one of you speak the truth with his neighbor, for we are members one of another. 26 Be angry and do not sin; do not let the sun go down on your anger, 27 and give no opportunity to the devil. 28 Let the thief no longer steal, but rather let him labor, doing honest work with his own hands, so that he may have something to share with anyone in need.
Eph 4:29 Let no corrupting talk come out of your mouths, but only such as is good for building up, as fits the occasion, that it may give grace to those who hear. 30 And do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption.
Eph 4:31 Let all bitterness and wrath and anger and clamor and slander be put away from you, along with all malice. 32 Be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you.
Self control is enabled by an inner man that desires to please God. When we focus on the most important things, to love God with all our being, and to love our neighbor as ourselves, we gain the power to live disciplined lives.
Col 3:2 Set your minds on things that are above, not on things that are on earth. 3 For you have died, and your life is hidden with Christ in God. 4 When Christ who is your life appears, then you also will appear with him in glory.
Col 3:5 Put to death therefore what is earthly in you: sexual immorality, impurity, passion, evil desire, and covetousness, which is idolatry. 6 On account of these the wrath of God is coming. 7 In these you too once walked, when you were living in them. 8 But now you must put them all away: anger, wrath, malice, slander, and obscene talk from your mouth.
Col 3:9 Do not lie to one another, seeing that you have put off the old self with its practices 10 and have put on the new self, which is being renewed in knowledge after the image of its creator.
And living a disciplined life means that we give up acting on the natural desires that are not pleasing to God. We no longer do things just because they make us feel good, but we learn to feel good about doing the things that are pleasing to God.