Here's some quotes from the apostles Paul and Peter on the training of the mind.
Those who live according to the sinful nature have their minds set on what that nature desires; but those who live in accordance with the Spirit have their minds set on what the Spirit desires. The mind of the sinful man is death, but the mind controlled by the Spirit is life and peace.
Do not conform any longer to the pattern of this world, but be transformed by the renewing of your mind. Then you will be able to test and approve what God's will is – his good, pleasing and perfect will.
But we have the mind of Christ.
1 Corinthians 2:16
You were taught, with regard to your former way of life, to put off your old self, which is being corrupted by its deceitful desires; to be made new in the attitude of your minds; and to put on the new self, created to be like God in true righteousness and holiness.
Your attitude should be the same as that of Christ Jesus.
Finally, brothers, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable – if anything is excellent or praiseworthy – think about such things.
Since, then, you have been raised with Christ, set your hearts on things above, where Christ is seated at the right hand of God. Set your minds on things above, not earthly things. For you died and your life is now hidden with Christ in God.
Be diligent in these matters; give yourself wholly to them, so that everyone may see your progress. Watch your life and doctrine closely. Persevere in them, because if you do, you will save both yourself and your hearers.
1 Timothy 15-16
Reflect on what I am saying, for the Lord will give you insight into all this.
2 Timothy 2:7
Therefore, prepare your minds for action; be self-controlled; set your hope fully on the grace to be given you when Jesus Christ is revealed.
1 Peter 1:13
The end of all things is near. Therefore be clear-minded and self-controlled so that you can pray.
1 Peter 4:7