Some people think that whatever pops into their head is what they have to think about. That’s a recipe for disaster. Thinking is a choice. Just as you exercise control over your body and how you behave, so God expects you to exercise control over your mind and what you think.

It takes your will to say yes, and then your actions must support that choice. The Holy Spirit gives you divine encouragement and empowerment to think the thoughts you have chosen to think—His thoughts, not ours.

For though we walk in the flesh, we do not war after the flesh: (For the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds;) Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ; And having in a readiness to revenge all disobedience, when your obedience is fulfilled. Do ye look on things after the outward appearance? If any man trust to himself that he is Christ’s, let him of himself think this again, that, as he is Christ’s, even so are we Christ’s.
2 Corinthians 10:3‭-‬7

“You can’t say, “My household serves the Lord,” while you’re renting a room to the enemy in your thought life. He’ll never stay put. There’s no way to rent him a room without eventually giving him the whole house.”