What does the Bible teach about self-discipline?

from the old testament

• It is good to be patient and to demonstrate self-discipline (Proverbs 16:32).
• Lacking self-control makes us vulnerable to harm (Proverbs 25:28).

from the new testament

• Humans don't generally like any control placed on us whether by ourselves, by others, or by God. God knows this; we learn in Hebrews 12:11 that, "For the moment all discipline seems painful rather than pleasant, but later it yields the peaceful fruit of righteousness to those who have been trained by it."
• Even as believers, we struggle with self-control in regards to sin. Paul describes this in Romans 7:15–20: "For I do not understand my own actions. For I do not do what I want, but I do the very thing I hate. Now if I do what I do not want, I agree with the law, that it is good. So now it is no longer I who do it, but sin that dwells within me. For I know that nothing good dwells in me, that is, in my flesh. For I have the desire to do what is right, but not the ability to carry it out. For I do not do the good I want, but the evil I do not want is what I keep on doing. Now if I do what I do not want, it is no longer I who do it, but sin that dwells within me."
• Self-control is a fruit of the Spirit (Galatians 5:22–23). Paul tell us that we should "walk by the Spirit, and you will not gratify the desires of the flesh" (Galatians 5:16).
• Indulging in the flesh is a lack of self-discipline. In Galatians 5:19–21, Paul describes what it means to walk in the flesh, "Now the works of the flesh are evident: sexual immorality, impurity, sensuality, idolatry, sorcery, enmity [hatred], strife [conflict], jealousy, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God."
• Self-discipline is a gift: "for God gave us a spirit not of fear but of power and love and self-control" (2 Timothy 1:7).
• Paul includes discipline or self-control as a qualification to be considered for a position as an elder in the church (Titus 1:7–9).
• Paul wrote in 1 Corinthians 9:24–27, “Do you not know that in a race all the runners run, but only one receives the prize? So run that you may obtain it. Every athlete exercises self-control in all things. They do it to receive a perishable wreath, but we an imperishable. So I do not run aimlessly; I do not box as one beating the air. But I discipline my body and keep it under control, lest after preaching to others I myself should be disqualified.” Paul set an example of self-discipline (see also Philippians 4:9).
• Self-discipline can be seen in the call to “work out your own salvation with fear and trembling, for it is God who works in you, both to will and to work for his good pleasure” (Philippians 2:12–13). We are to actively and intentionally work toward spiritual growth, ultimately trusting and relying on God to complete His good work in us (Philippians 1:6).
• Paul told Timothy to “train yourself for godliness” (1 Timothy 4:7). In part, this was by “being trained in the words of the faith and of the good doctrine that you have followed” (1 Timothy 4:6). Self-discipline is at play when we intentionally spend time in God’s Word to be shaped by His truth and His Spirit through it (John 17:17; 2 Timothy 3:16–17). Other so-called spiritual disciplines—like prayer, fellowship, solitude, fasting, confession, giving, etc.—are also ways we can demonstrate self-discipline to intentionally train ourselves in godliness.
• We also exercise self-discipline when we “take every thought captive to obey Christ” (2 Corinthians 10:5). It takes self-discipline to intentionally think about “whatever is true, whatever is honorable, whatever is just, whatever is pure, whatever is lovely, whatever is commendable, if there is any excellence, if there is anything worthy of praise” (Philippians 4:8).
• Self-discipline can be seen in our habits of fellowship (Hebrews 10:19–25) and service (Romans 12; Galatians 6:1–10).
• Ultimately, self-discipline has to do with yielding to the work of the Holy Spirit both to set aside sin and to intentionally live in the ways God would have us live (see Galatians 5, Ephesians 4, Colossians 3, and Romans 12). Our life habits result in fruit (Matthew 7:15–20). When we exercise self-discipline to consistently engage in things that honor God and lead to growth, we are more likely to experience the joy of abiding in Christ and abundant life in Him (see John 10:10; 15:1–17).

implications for today

Self-discipline does not always seem pleasant at first (Hebrews 12:11). Doing things we don’t want to do, or not doing things we do want to do, is not natural. But when we recognize that God’s ways are for our best, and that our sinful desires lead only to death, it becomes simpler to desire God’s ways (James 1:12–18). The more we know God, the more we will love Him and want to live according to His life-giving ways. Also, the more we know God, the more we’ll be able to rely on His Spirit to give us the self-discipline to engage in godly living (Romans 12:1–2). Thankfully, a simple reality of human behavior is that the more we do something, the more natural it becomes; self-discipline will build on itself. Generally speaking, we reap what we sow (Galatians 6:7–8). This means that the more we engage in self-discipline, the more normal those behaviors will feel. And, when we’re self-disciplined about things that God promises bring true life, the more of that blessing we will experience. The more we are engaged in our life with God, the more likely we are to see sin for what it is and desire to put it to death. And thus, the more likely we’ll be able to exercise Spirit-empowered self-control over our sinful desires (1 Corinthians 10:13).

Neither self-discipline nor self-control will ever be easy. Really, true self-control is not about our own power to control ourselves, but the power of Christ to continue His work of sanctifying us, making us more like Him. Jesus lived His entire life "without sin" (Hebrews 4:15). "He committed no sin, neither was deceit found in his mouth" (1 Peter 2:22). He persevered in the face of great anxiety (Luke 22:44) and when He was confronted by false accusations (Matthew 27:14). We should seek Jesus when our lives are spinning out of control, when we refuse to do what we should do, and when we can't stop sinning. Commit to prayer and ask Him to change you, then you will be able to say as Paul said, "I thank him who has given me strength, Christ Jesus our Lord, because he judged me faithful, appointing me to his service" (1 Timothy 1:12).