Resisting is an act of the will. It is best to speak it out. Sometimes it is necessary to command an evil spirit out of an individual. I've commanded an evil spirit out of my own life. If you make it clear before God that your will is to be free, He will back you up. We have the power and authority in Christ.
The battle begins in the mind. If we will take care our thought life, much trouble can be avoided.
A simple example may help. I was on my way to work when I had a thought that it was going to be a freezing winter and I should buy some new clothes. It came out of the blue. I rejected the thought and took no action. The following winter was milder than usual. The thought was a setup. If I'd accepted the thought, there would have been another thought trying to get me to act on it. Then another and another. That can lead to serious mental issues. It's devastating when you realised that you've been deceived - I know from experience.
Another more serious incident. I was driving home when I went into a rain storm. I could see almost nothing. The windscreen wipers could not cope. I was on a four lane freeway. Cars were going past me at speed. How they dared to go so fast, I don't know. I freaked. If I'd slowed down, I may have been tail-ended. As I could barely see, I may have run into a slower car ahead. I asked the Lord to calm the storm. He said, "I did not send it and I will not take it away". Immediately I remembered how Lord Jesus dealt with the storm that he went through. I rebuked the storm. Within moments the rain ceased and I was in the clear.
I recommend "War on the Saints" for anyone who wants to know about spiritual warfare.
The scriptural basis for this warfare is 2 Corinthians 10: 4 & 5
The weapons of our warfare are not the weapons of the world. Instead, they have divine power to demolish strongholds.
We tear down arguments and every presumption set up against the knowledge of God; and we take captive every thought to make it obedient to Christ.
"Strongholds" are lies that have been planted in our minds because we were not aware of the spiritual war that is taking place. I spent years worrying about my teeth. Then I needed an extraction. The dentist told me I had a jaw like iron and really tough teeth. That was about 25 years ago. I've not needed any dental work since. My worry was based on a lie. The truth dispels the lie!