Several times in my life I have felt myself to be attacked by malign psychic forces. Sometimes this has been in dreams and I describe an incident from not too long ago here. That was very dramatic and unmistakeable but these attacks can also happen in waking hours and then they are usually not so obvious. For instance, we are attacked through our thoughts and emotions which can be manipulated, if we allow them to be, by the dark forces to bring us down into the kind of world they inhabit, one of anger, delusion and lies. My teachers told me that the more progress you make on the path, the more you are attacked by these beings and that has been my experience.
There are various ways to protect yourself against these attacks. One very simple way is just to watch out for your thoughts and emotions and not allow these to be corrupted. Keep your thoughts on the full reality of God, seeing everything in his light, and do not let your feelings become contaminated by anger, fear or, a particular weakness of mine, irritation. You can still feel these emotions but try to place them in the context of God's love which can burn them all up. I don't pretend this is easy. It's the work of a lifetime but that's what we are here to do. Life is work, specifically spiritual work, and our labours in this world will be rewarded in the next.
Of all the weapons at our disposal to fight evil I have found (not that it's a new discovery!) there is none more potent than the name of Jesus. This is a kind of gleaming white sword of fire that can cut right through any demonic attack. "In the name of Jesus Christ, Son of God, depart!" There is no more powerful utterance. Not only does the very name appear to disarm the demons but by appealing to Jesus you summon his aid, both in your own imagination, which is important, and in reality. You are bringing his presence to the field. In a very real sense where his name is spoken, there he is.
Non-religious people might just regard this as a kind of mental trick, a spiritual version of a placebo which works because you believe it will work. They might point to the fact that Jesus's name varies slightly from language to language. But that is because they are viewing the operation from within the limitations of their own materialistic worldview. The truth is that the name of Jesus in any language has a spiritual power beyond all others because it is a form of Jesus himself. In the spiritual world our names are us and we are our names. It is almost like a face. It is certainly a real aspect of the person. And because Jesus is the greatest person, his name is the greatest name. Just to say the name Jesus brings Jesus into your life, though the greater your faith and love the fuller will be his presence. He is life and truth and so no wonder the demons, who have set themselves against life and truth, flee when he comes.