A decent smattering of what the Bible says:

A man without self-control is like a city broken into and left without walls. (Proverbs 25:28)

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. (1 Corinthians 9:25-27)

But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control; against such things there is no law. And those who belong to Christ Jesus have crucified the flesh with its passions and desires. (Galatians 5:22-24)

God gave us a spirit not of fear but of power and love and self-control. (2 Timothy 1:7)

But understand this, that in the last days there will come times of difficulty. For people will be lovers of self, lovers of money, proud, arrogant, abusive, disobedient to their parents, ungrateful, unholy, heartless, unappeasable, slanderous, without self-control, brutal, not loving good, treacherous, reckless, swollen with conceit, lovers of pleasure rather than lovers of God, having the appearance of godliness, but denying its power. Avoid such people. (2 Timothy 3:1-5)

For this very reason, make every effort to supplement your faith with virtue, and virtue with knowledge, and knowledge with self-control, and self-control with steadfastness, and steadfastness with godliness,  and godliness with brotherly affection, and brotherly affection with love.  For if these qualities are yours and are increasing, they keep you from being ineffective or unfruitful in the knowledge of our Lord Jesus Christ. (2 Peter 1:5-8)